Difference between revisions of "API:EPrints/Database"

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<!-- Pod2Wiki=_preamble_  
 
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  -->{{API}}{{Pod2Wiki}}{{API:Source|file=perl_lib/EPrints/Database.pm|package_name=EPrints::Database}}[[Category:API|DATABASE]][[Category:API:EPrints/Database|DATABASE]]<div><!-- Edit below this comment -->
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  -->{{API}}{{Pod2Wiki}}{{API:Source|file=EPrints/Database.pm|package_name=EPrints::Database}}[[Category:API|DATABASE]][[Category:API:EPrints/Database|DATABASE]]<div><!-- Edit below this comment -->
  
  
 
<!-- Pod2Wiki=_private_ --><!-- Pod2Wiki=head_name -->
 
<!-- Pod2Wiki=_private_ --><!-- Pod2Wiki=head_name -->
 
==NAME==
 
==NAME==
'''EPrints::Database''' - a connection to the SQL database for an eprints session
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'''EPrints::Database''' - a connection to the SQL database for an eprints session.
  
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</div>
==SYNOPSIS==
 
  $db = $repo-&gt;database
 
  $sth = $db-&gt;prepare("SELECT 'hello, world!'");
 
  $sth-&gt;execute;
 
  print $sth-&gt;fetchrow_arrayref-&gt;[0], "\n";
 
 
 
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<!-- Pod2Wiki=head_description -->
 
==DESCRIPTION==
 
==DESCRIPTION==
 
EPrints Database Access Module
 
EPrints Database Access Module
  
Provides access to the backend database. All database access is performed via this module to 1) provide cross-database support and 2) improve security through enforcing proper quoting of SQL values.
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Provides access to the backend database. All database access done via this module, in the hope that the backend can be replaced as easily as possible.
  
In most use-cases it should not be necessary to use the database module directly. Instead you should use [[API:EPrints/DataSet|EPrints::DataSet]] or [[API:EPrints/MetaField|EPrints::MetaField]] accessor methods to access objects and field values respectively.
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In most use-cases it should not be necessary to use the database module directly. Instead you should use [[API:EPrints/DataSet|EPrints::DataSet]] or [[API:EPrints/MetaField|EPrints::MetaField]] accessor methods to access objects and field values respectively.
  
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</div>
 
<!-- Pod2Wiki=head_cross_database_support -->
 
<!-- Pod2Wiki=head_cross_database_support -->
 
===Cross-database Support===
 
===Cross-database Support===
Any use of SQL statements must use [[API:EPrints/Database#quote_identifier|quote_identifier]] to quote database tables and columns and [[API:EPrints/Database#quote_value|quote_value]] to quote values. The only exception to this are the EPrints::Database::* modules which provide database-driver specific extensions.
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Any use of SQL statements must use [[API:EPrints/Database#quote_identifier|quote_identifier]] to quote database tables and columns and quote_value to quote values. The only exception to this are the EPrints::Database::* modules which provide database-driver specific extensions.  
  
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</div>
 
<!-- Pod2Wiki=head_quoting_sql_values -->
 
<!-- Pod2Wiki=head_quoting_sql_values -->
 
===Quoting SQL Values===
 
===Quoting SQL Values===
By convention variables that contain already quoted values are prefixed with 'Q_' so they can be easily recognised when used in string interpolation:
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By convention variables that contain already quoted values are prefixed with <tt>Q_</tt> so they can be easily recognised when used in string interpolation:  
  
  my $Q_value = $db-&gt;quote_value( "Hello, World!" );
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my $Q_value = $db-&gt;quote_value( "Hello, World!" );
  $db-&gt;do("SELECT $Q_value");
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$db-&gt;do("SELECT $Q_value");
 
    
 
    
Where possible you should avoid quoting values yourself, instead use a method that accepts unquoted values which will (safely) do the work for you.
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Where possible you should avoid quoting values yourself, instead use a method that accepts unquoted values which will (safely) do the work for you.
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</div>
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<!-- Pod2Wiki=head_constants -->
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==CONSTANTS==
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All the <tt>SQL_</tt> column types defined by Perl module {{API:PodLink|file=DBI|package_name=DBI|section=|text=DBI}} and the  following:
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<!-- Pod2Wiki=item_sql_null -->
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===SQL_NULL===
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A column value is undefined.
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<!-- Pod2Wiki=item_sql_not_null -->
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===SQL_NOT_NULL===
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 +
A column value is defined.
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<!-- Pod2Wiki=head_instance_variables -->
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==INSTANCE VARIABLES==
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<!-- Pod2Wiki=item_$self->{session} -->
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===$self-&gt;{session}===
 +
 +
The [[API:EPrints/Session|EPrints::Session]] which is associated with this database  connection.
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===$self-&gt;{debug}===
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If <tt>true</tt> then SQL is logged.
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<!-- Pod2Wiki=item_$self->{dbh} -->
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===$self-&gt;{dbh}===
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The handle on the actual database connection.
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<!-- Pod2Wiki=head_methods -->
 
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==METHODS==
 
==METHODS==
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</div>
 
<!-- Pod2Wiki=head_database -->
 
<!-- Pod2Wiki=head_database -->
 
===Database===
 
===Database===
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<!-- Pod2Wiki=item_new -->
 
<!-- Pod2Wiki=item_new -->
 
====new====
 
====new====
  
<source lang="perl">$db = EPrints::Database->new( $repo )
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$db = EPrints::Database-&gt;new( $repo, [ %opts ] )
 +
Create a connection to the database.
  
</source>
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Options:
Create a connection to the database.
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  db_connect - Boolean. Also connect to the database (default: true).
  
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<!-- Pod2Wiki=item_create -->
 
<!-- Pod2Wiki=item_create -->
 
====create====
 
====create====
  
<source lang="perl">$db = $db->create( $username, $password )
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$db = $db-&gt;create( $username, $password )
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Create and connect to a new database using user account <tt>$username</tt>  and <tt>$password</tt>.
  
</source>
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Create and connect to a new database using super user account $username and $password.
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<!-- Pod2Wiki=item_build_connection_string -->
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====build_connection_string====
 +
 
 +
$dbstr = EPrints::Database::build_connection_string( %params )
 +
Build the string to use to connect to the database via {{API:PodLink|file=DBI|package_name=DBI|section=|text=DBI}}.
 +
 
 +
Parameters:
 +
dbname - Database name (REQUIRED).
 +
dbdriver - Database driver (e.g. mysql, Oracle, pgsql, default: mysql).
 +
dbhost - Database host.  Assumes localhost if unset.
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dbport - Port to connect to database host.  Assumes default for driver if unset.
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dbsock - Socket file to connect to database through.
  
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<!-- Pod2Wiki=item_connect -->
 
<!-- Pod2Wiki=item_connect -->
 
====connect====
 
====connect====
  
<source lang="perl">$ok = $db->connect
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$db-&gt;connect()
 
 
</source>
 
 
Connects to the database.  
 
Connects to the database.  
  
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</div>
 
<!-- Pod2Wiki=item_disconnect -->
 
<!-- Pod2Wiki=item_disconnect -->
 
====disconnect====
 
====disconnect====
  
<source lang="perl">$db->disconnect
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$db-&gt;disconnect()
 
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Disconnects from the EPrints database. Should always be done before  any script exits.
</source>
 
Disconnects from the EPrints database.
 
  
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<!-- Pod2Wiki=item_set_debug -->
 
<!-- Pod2Wiki=item_set_debug -->
 
====set_debug====
 
====set_debug====
  
<source lang="perl">$db->set_debug( $boolean )
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$db-&gt;set_debug( $boolean )
 
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Set the SQL debug mode to <tt>true</tt> or <tt>false</tt>.
</source>
 
Set the SQL debug mode to true or false.
 
  
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<!-- Pod2Wiki=item_set_version -->
 
<!-- Pod2Wiki=item_set_version -->
 
====set_version====
 
====set_version====
  
<source lang="perl">$db->set_version( $versionid );
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$db-&gt;set_version( $versionid );
 
+
Set the version id table in the SQL database to the given <tt>versionid</tt> (used by the upgrade script).
</source>
 
Set the version id table in the SQL database to the given value (used by the upgrade script).
 
  
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<!-- Pod2Wiki=item_get_version -->
 
====get_version====
 
====get_version====
  
<source lang="perl">$version = $db->get_version
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$version = $db-&gt;get_version
 
+
Returns the current database schema version.  
</source>
 
Returns the current database schema version.
 
  
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<!-- Pod2Wiki=item_is_latest_version -->
 
<!-- Pod2Wiki=item_is_latest_version -->
 
====is_latest_version====
 
====is_latest_version====
  
<source lang="perl">$boolean = $db->is_latest_version
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$boolean = $db-&gt;is_latest_version
 
+
Return <tt>true</tt> if the SQL tables are in the correct configuration for this edition of eprints. Otherwise, <tt>false</tt>.
</source>
 
Return true if the database schema is in the correct configuration for this version of eprints. Otherwise false.
 
  
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<!-- Pod2Wiki=item_get_server_version -->
 
<!-- Pod2Wiki=item_get_server_version -->
 
====get_server_version====
 
====get_server_version====
  
<source lang="perl">$version = $db->get_server_version
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$version = $db-&gt;get_server_version
 
 
</source>
 
 
Return the database server version.
 
Return the database server version.
  
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<!-- Pod2Wiki=item_get_default_charset -->
 
<!-- Pod2Wiki=item_get_default_charset -->
 
====get_default_charset====
 
====get_default_charset====
  
<source lang="perl">$charset = $db->get_default_charset( LANGUAGE )
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$charset = $db-&gt;get_default_charset
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Return the character set to use.
  
</source>
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Returns <tt>undef</tt> if character sets are unsupported.
Return the character set to use for LANGUAGE.
 
 
 
Returns undef if character sets are unsupported.
 
  
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<!-- Pod2Wiki=item_get_default_collation -->
 
<!-- Pod2Wiki=item_get_default_collation -->
 
====get_default_collation====
 
====get_default_collation====
  
<source lang="perl">$collation = $db->get_default_collation( LANGUAGE )
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$collation = $db-&gt;get_default_collation( $lang )
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Return the collation to use for language <tt>$lang</tt>.
  
</source>
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Returns <tt>undef</tt> if collation is unsupported.
Return the collation to use for LANGUAGE.
 
 
 
Returns undef if collation is unsupported.
 
  
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<!-- Pod2Wiki=item_get_driver_name -->
 
====get_driver_name====
 
====get_driver_name====
  
<source lang="perl">$driver = $db->get_driver_name
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$driver = $db-&gt;get_driver_name
 
 
</source>
 
 
Return the database driver name.
 
Return the database driver name.
  
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<!-- Pod2Wiki=item_error -->
 
====error====
 
====error====
  
<source lang="perl">$errstr = $db->error
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$errstr = $db-&gt;error()
 
 
</source>
 
 
Return a string describing the last SQL error.
 
Return a string describing the last SQL error.
  
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<!-- Pod2Wiki=item_retry_error -->
 
====retry_error====
 
====retry_error====
  
<source lang="perl">$bool = $db->retry_error
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$boolean = $db-&gt;retry_error()
 
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Returns a boolean for whether the database error is a retry error.
</source>
 
Returns true if the current error is a retry error.
 
  
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<!-- Pod2Wiki=item_duplicate_error -->
 
====duplicate_error====
 
====duplicate_error====
  
<source lang="perl">$bool = $db->duplicate_error
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$boolean = $db-&gt;duplicate_error()
 
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Returns a boolean for whether the database error is a duplicate error.
</source>
 
Returns true if the current error is a PRIMARY KEY or UNIQUE error.
 
  
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<!-- Pod2Wiki=item_begin -->
 
====begin====
 
====begin====
  
<source lang="perl">$db->begin
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$db-&gt;begin()
 
 
</source>
 
 
Begin a transaction.
 
Begin a transaction.
  
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<!-- Pod2Wiki=item_commit -->
 
<!-- Pod2Wiki=item_commit -->
 
====commit====
 
====commit====
  
<source lang="perl">$db->commit
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$db-&gt;commit()
 
 
</source>
 
 
Commit the previously begun transaction.
 
Commit the previously begun transaction.
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
 +
</div>
 
<!-- Pod2Wiki=item_rollback -->
 
<!-- Pod2Wiki=item_rollback -->
 
====rollback====
 
====rollback====
  
<source lang="perl">$db->rollback
+
$db-&gt;rollback()
 
+
Rollback the partially completed transaction.
</source>
 
Roll-back the current transaction.
 
  
 +
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 +
</div>
 
<!-- Pod2Wiki=item_type_info -->
 
<!-- Pod2Wiki=item_type_info -->
 
====type_info====
 
====type_info====
  
<source lang="perl">$type_info = $db->type_info( DATA_TYPE )
+
$type_info = $db-&gt;type_info( $data_type )
 
 
</source>
 
 
See {{API:PodLink|file=DBI|package_name=DBI|section=type_info|text=DBI/type_info}}.
 
See {{API:PodLink|file=DBI|package_name=DBI|section=type_info|text=DBI/type_info}}.
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
 +
</div>
 
<!-- Pod2Wiki=item_get_column_type -->
 
<!-- Pod2Wiki=item_get_column_type -->
 
====get_column_type====
 
====get_column_type====
  
<source lang="perl">$real_type = $db->get_column_type( NAME, TYPE, NOT_NULL, [ LENGTH/PRECISION ], [ SCALE ], %opts )
+
$real_type = $db-&gt;get_column_type( $name, $data_type, $not_null, [ $length, $scale, %opts ] )
 
+
Returns a SQL column definition for <tt>$name</tt> of type <tt>$type</tt>, usually something like:
</source>
 
Returns a SQL column definition for NAME of type TYPE, usually something like:
 
  
 
   $name $type($length,$scale) [ NOT NULL ]
 
   $name $type($length,$scale) [ NOT NULL ]
 
    
 
    
If NOT_NULL is true column will be set "not null".
+
If <tt>$not_null</tt> is <tt>true</tt> column will be set to <tt>NOT NULL</tt>.
  
LENGTH/PRECISION and SCALE control the maximum lengths of character or decimal types (see below).
+
<tt>$length</tt> and <tt>$scale</tt> control the maximum lengths of character or decimal types (see below).
  
 
Other options available to refine the column definition:
 
Other options available to refine the column definition:
Line 319: Line 446:
 
   sorted - whether this column will be used to order by
 
   sorted - whether this column will be used to order by
 
    
 
    
'''langid''' is mapped to real database values by the "dblanguages" configuration option. The database may not be able to order the request column type in which case, if '''sorted''' is true, the database may use a substitute column type.
+
'''langid''' is mapped to real database values by the "dblanguages" configuration option. The database may not be able to order the request column type in which case, if <tt>sorted</tt> is true, the database may use a substitute column type.
  
TYPE is the SQL type. The types are constants defined by this module, to import them use:
+
<tt>$data_type</tt> is the SQL type. The types are constants defined by this module, to import them use:
  
 
   use EPrints::Database qw( :sql_types );
 
   use EPrints::Database qw( :sql_types );
 
    
 
    
Supported types (n = requires LENGTH argument):
+
Supported types (n = requires <tt>$length</tt> argument):
  
Character data: SQL_VARCHAR(n), SQL_LONGVARCHAR, SQL_CLOB.
+
Character data: <tt>SQL_VARCHAR(n)</tt>, <tt>SQL_LONGVARCHAR</tt>, <tt>SQL_CLOB</tt>.
  
Binary data: SQL_VARBINARY(n), SQL_LONGVARBINARY.
+
Binary data: <tt>SQL_VARBINARY(n)</tt>, <tt>SQL_LONGVARBINARY</tt>.
  
Integer data: SQL_TINYINT, SQL_SMALLINT, SQL_INTEGER, SQL_BIGINT.
+
Integer data: <tt>SQL_TINYINT</tt>, <tt>SQL_SMALLINT</tt>, <tt>SQL_INTEGER</tt>, <tt>SQL_BIGINT</tt>.
  
Floating-point data: SQL_REAL, SQL_DOUBLE.
+
Floating-point data: <tt>SQL_REAL</tt>, <tt>SQL_DOUBLE</tt>.
  
Time data: SQL_DATE, SQL_TIME.
+
Time data: <tt>SQL_DATE</tt>, <tt>SQL_TIME</tt>.
  
 
The actual column types used will be database-specific.
 
The actual column types used will be database-specific.
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=head_schema_manipulation -->
+
</div>
===Schema Manipulation===
+
<!-- Pod2Wiki=head_basic_sql_operations -->
 +
===Basic SQL Operations===
 +
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<!-- Pod2Wiki=item_create_archive_tables -->
+
</div>
====create_archive_tables====
+
<!-- Pod2Wiki=item_do -->
 
+
====do====
<source lang="perl">$success = $db->create_archive_tables
 
  
</source>
+
$success = $db-&gt;do( $sql )
Create all the SQL tables for each dataset.
+
Execute the given <tt>$sql</tt>.
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_drop_archive_tables -->
+
</div>
====drop_archive_tables====
+
<!-- Pod2Wiki=item_prepare -->
 +
====prepare====
  
<source lang="perl">$db->drop_archive_tables()
+
$sth = $db-&gt;prepare( $sql )
 +
Prepare the given <tt>$sql</tt> and return a handle on it.
  
</source>
+
Use the <tt>execute</tt> method on the returned {{API:PodLink|file=DBI|package_name=DBI|section=|text=DBI}} handle to execute the SQL:
Destroy all tables used by eprints in the database.
 
  
 +
  my $sth = $db-&gt;prepare_select( "SELECT 'Hello, World'" );
 +
  $sth-&gt;execute;
 +
 
 +
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<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_create_version_table -->
+
</div>
====create_version_table====
+
<!-- Pod2Wiki=item_prepare_select -->
 +
====prepare_select====
 +
 
 +
$sth = $db-&gt;prepare_select( $sql, [ %options ] )
 +
Prepare a <tt>SELECT</tt> statement <tt>$sql</tt> and return a handle to it. After  preparing a statement use <tt>execute()</tt> to execute it.
  
<source lang="perl">$db->create_version_table
+
Returns a {{API:PodLink|file=DBI|package_name=DBI|section=|text=DBI}} statement handle.
  
</source>
+
The <tt>LIMIT</tt> SQL keyword is not universally supported, to specify this  use the <tt>limit</tt> option.
Make the version table (and set the only value to be the current version of eprints).
 
  
 +
Options:
 +
 +
  limit - limit the number of rows returned
 +
  offset - return '''limit''' number of rows after offset
 +
 
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_drop_version_table -->
+
</div>
====drop_version_table====
+
<!-- Pod2Wiki=item_execute -->
 
+
====execute====
<source lang="perl">$db->drop_version_table
 
  
</source>
+
$success = $db-&gt;execute( $sth, $sql )
Drop the version table.
+
Execute the SQL prepared earlier in the <tt>$sth</tt>. <tt>$sql</tt> is only  required for debugging purposes.
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_create_dataset_tables -->
+
</div>
====create_dataset_tables====
+
<!-- Pod2Wiki=item_update -->
 +
====update====
  
<source lang="perl">$success = $db->create_dataset_tables( $dataset )
+
$success = $db-&gt;update( $dataset, $data, $changed )
 +
Updates a <tt>EPrints::DataObj</tt> from <tt>$dataset</tt> with the given <tt>$data</tt>.  The primary key field (e.g. <tt>eprintid</tt>) value must be included.
  
</source>
+
Updates the <tt>ordervalues</tt> if the <tt>$dataset</tt> is  {{API:PodLink|file=EPrints/DataSet#ordered|package_name=EPrints::DataSet#ordered|section=|text=ordered}}.
Create all the SQL tables for a single dataset.
 
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_drop_dataset_tables -->
+
</div>
====drop_dataset_tables====
+
<!-- Pod2Wiki=item__update -->
 +
====_update====
 +
 
 +
$rows = $db-&gt;_update( $tablename, $keycols, $keyvals, $columns, @values )
 +
Updates <tt>$columns</tt> in <tt>$tablename</tt> with <tt>@values</tt> where <tt>$keycols</tt>  equals <tt>$keyvals</tt> and returns the number of rows affected.
  
<source lang="perl">$db->drop_dataset_tables( $dataset )
+
N.B. If no rows are affected, the result is still <tt>true</tt>,  see {{API:PodLink|file=DBI|package_name=DBI|section=|text=DBI}}'s <tt>execute()</tt> method.
  
</source>
+
This is an internal method.
Drop all the SQL tables for a single dataset.
 
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_create_dataset_index_tables -->
+
</div>
====create_dataset_index_tables====
+
<!-- Pod2Wiki=item_insert -->
 +
====insert====
  
<source lang="perl">$success = $db->create_dataset_index_tables( $dataset )
+
$success = $db-&gt;insert( $table, $columns, @values )
 
+
Inserts <tt>@values</tt> into the table <tt>$table</tt>. If <tt>$columns</tt> is defined  it will be used as a list of columns to insert into. <tt>@values</tt> is a list of arrays containing values to insert. These will be quoted before  insertion.
</source>
 
Create all the index tables for a single dataset.
 
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_create_dataset_ordervalues_tables -->
+
</div>
====create_dataset_ordervalues_tables====
+
<!-- Pod2Wiki=item_insert_quoted -->
 
+
====insert_quoted====
<source lang="perl">$success = $db->create_dataset_ordervalues_tables( $dataset )
 
  
</source>
+
$success = $db-&gt;insert_quoted( $table, $columns, @qvalues )
Create all the ordervalues tables for a single dataset.
+
Inserts values into the table <tt>$table</tt>. If <tt>$columns</tt> is defined it  will be used as a list of columns to insert into. <tt>@qvalues</tt> is a list of arrays containing values to insert. These will NOT be quoted  before insertion - care must be exercised!
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_has_dataset -->
+
</div>
====has_dataset====
+
<!-- Pod2Wiki=item_delete_from -->
 
+
====delete_from====
<source lang="perl">$db->has_dataset( $dataset )
 
  
</source>
+
$success = $db-&gt;delete_from( $table, $columns, @values )
Returns true if $dataset exists in the database or has no database tables.
+
Perform a SQL <tt>DELETE FROM</tt> <tt>$table</tt> using <tt>$columns</tt> to build a  where clause. <tt>@values</tt> is a list of array references of values in the same order as <tt>$columns</tt>.
  
This does not check that all fields are configured - see has_field().
+
If you want to clear a table completely use <tt>clear_table()</tt>.
  
 +
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<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_has_field -->
+
</div>
====has_field====
+
<!-- Pod2Wiki=item_count_table -->
 
+
====count_table====
<source lang="perl">$db->has_field( $dataset, $field )
 
  
</source>
+
$n = $db-&gt;count_table( $tablename )
Returns true if $field is in the database for $dataset.
+
Return the number of rows in the specified SQL table with  <tt>$tablename</tt>.
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_add_field -->
+
</div>
====add_field====
+
<!-- Pod2Wiki=item_clear_table -->
 +
====clear_table====
  
<source lang="perl">$db->add_field( $dataset, $field [, $force ] )
+
$db-&gt;clear_table( $tablename )
 +
Clears all records from the given table with <tt>$tablename</tt>. Use with  caution!
  
</source>
+
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
Add $field to $dataset's tables.
+
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<!-- Edit below this comment -->
  
If $force is true will modify/replace an existing column (use with care!).
 
  
 +
<!-- Pod2Wiki= -->
 +
</div>
 +
<!-- Pod2Wiki=head_quoting -->
 +
===Quoting===
 +
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<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_remove_field -->
+
</div>
====remove_field====
+
<!-- Pod2Wiki=item_prep_int -->
 
+
====prep_int====
<source lang="perl">$db->remove_field( $dataset, $field )
 
  
</source>
+
$mungedvalue = EPrints::Database::prep_int( $value )
Remove $field from $dataset's tables.
+
Escape numerical <tt>$value</tt> for an SQL statement. <tt>undef</tt> becomes  <tt>NULL</tt>. Anything else becomes a number (zero if needed).
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_rename_field -->
+
</div>
====rename_field====
+
<!-- Pod2Wiki=item_prep_value -->
 +
====prep_value====
 +
 
 +
$mungedvalue = EPrints::Database::prep_value( $value )
 +
Escape <tt>$value</tt> for an SQL statement. Modify value such that <tt>"</tt>  becomes <tt>\"</tt> and <tt>\</tt> becomes <tt>\\</tt> and <tt>'</tt> becomes <tt>\'</tt>.
 +
 
 +
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<!-- Edit below this comment -->
  
<source lang="perl">$ok = $db->rename_field( $dataset, $field, $old_name )
 
  
</source>
+
<!-- Pod2Wiki= -->
Rename a $field in the database from it's old name $old_name.
+
</div>
 +
<!-- Pod2Wiki=item_prep_like_value -->
 +
====prep_like_value====
  
Returns true if the field was successfully renamed.
+
$mungedvalue = EPrints::Database::prep_like_value( $value )
 +
Escape <tt>$value</tt> for an SQL <tt>LIKE</tt> clause. In addition to <tt>'</tt> <tt>"</tt>  and <tt>\</tt> also escapes <tt>%</tt> and <tt>_</tt>.
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_create_table -->
+
</div>
====create_table====
+
<!-- Pod2Wiki=item_quote_value -->
 +
====quote_value====
 +
 
 +
$str = $db-&gt;quote_value( $value )
 +
Return a quoted version of <tt>$value</tt>. To quote a <tt>LIKE</tt> value  you should use:
  
<source lang="perl">$success = $db->create_table( $tablename, $setkey, @fields );
+
$db-&gt;quote_value( EPrints::Database::prep_like_value( $foo ) . '%' );
 +
 
 +
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 +
<!-- Edit below this comment -->
  
</source>
 
Creates a new table $tablename based on @fields.
 
  
The first $setkey number of fields are used for a primary key.
+
<!-- Pod2Wiki= -->
 +
</div>
 +
<!-- Pod2Wiki=item_quote_int -->
 +
====quote_int====
  
 +
$str = $db-&gt;quote_int( $value )
 +
Return a quoted integer for <tt>$value</tt>.
 +
 +
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<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_create_foreign_key -->
+
</div>
====create_foreign_key====
+
<!-- Pod2Wiki=item_quote_binary -->
 
+
====quote_binary====
<source lang="perl">$ok = $db->create_foreign_key( $main_table, $aux_table, $key_field )
 
  
</source>
+
$str = $db-&gt;quote_binary( $bytes )
Create a foreign key relationship between $main_table and $aux_table using the $key_field.
+
Some databases (Oracle/PostgreSQL) require transforms of binary data  to work correctly.
  
This will cause records in $aux_table to be deleted if the equivalent record is deleted from $main_table.
+
This method should be called on data <tt>$bytes</tt> containing null bytes  or back-slashes before being passed on [[API:EPrints/Database#quote_value|quote_value]].
  
 +
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 +
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<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_create_counters -->
+
</div>
====create_counters====
+
<!-- Pod2Wiki=item_quote_ordervalue -->
 
+
====quote_ordervalue====
<source lang="perl">$success = $db->create_counters
 
  
</source>
+
$str = $db-&gt;quote_ordervalue( $field, $value )
Create the counters used to store the highest current id of eprints, users etc.
+
Some databases (Oracle) can't order by <tt>CLOB</tt>s so need special  treatment when creating the ordervalues tables. This method allows any  fixing-up required for string data <tt>$value</tt> for <tt>$field</tt> before it's  inserted.
  
 +
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<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_has_counter -->
+
</div>
====has_counter====
+
<!-- Pod2Wiki=item_quote_identifier -->
 +
====quote_identifier====
  
<source lang="perl">$success = $db->has_counter( $counter )
+
$str = $db-&gt;quote_identifier( @parts )
 
+
Quote a database identifier (e.g. table names). Multiple <tt>@parts</tt>  will be joined by dots (<tt>.</tt>).
</source>
 
Returns true if $counter exists.
 
  
 +
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 +
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<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_create_counter -->
+
</div>
====create_counter====
+
<!-- Pod2Wiki=item_prepare_regexp -->
 
+
====prepare_regexp====
<source lang="perl">$success = $db->create_counter( $name )
 
  
</source>
+
$sql = $db-&gt;prepare_regexp( $col, $value )
Create and initialise to zero a new counter called $name.
+
The syntax used for regular expressions varies across databases. This  method takes two quoted string and returns a SQL expression that will  apply the quoted regexp <tt>$value</tt> to the quoted column <tt>$col</tt>.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_remove_counters -->
+
</div>
====remove_counters====
+
<!-- Pod2Wiki=item_sql_as -->
 
+
====sql_as====
<source lang="perl">$success = $db->remove_counters
 
  
</source>
+
$sql = $db-&gt;sql_AS()
Destroy all counters.
+
Returns the syntactic glue to use when aliasing. SQL 92 databases will  happily use <tt>AS</tt> but some databases (Oracle) will not accept it.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_drop_counter -->
+
</div>
====drop_counter====
+
<!-- Pod2Wiki=item_sql_like -->
 +
====sql_like====
 +
 
 +
$sql = $db-&gt;sql_LIKE()
 +
Returns the syntactic glue to use when making a case-insensitive  <tt>LIKE</tt>. PostgreSQL requires <tt>ILIKE</tt> while everything else uses  <tt>LIKE</tt> and the column collation.
  
<source lang="perl">$success = $db->drop_counter( $name )
+
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 +
<!-- Edit below this comment -->
  
</source>
 
Destroy the counter named $name.
 
  
 +
<!-- Pod2Wiki= -->
 +
</div>
 +
<!-- Pod2Wiki=head_counters -->
 +
===Counters===
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
<!-- Edit below this comment -->
  
  
 
<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
 +
</div>
 
<!-- Pod2Wiki=item_counter_current -->
 
<!-- Pod2Wiki=item_counter_current -->
 
====counter_current====
 
====counter_current====
  
<source lang="perl">$n = $db->counter_current( $counter )
+
$n = $db-&gt;counter_current( $counter )
 
+
Return the value of the previous counter_next on <tt>$counter</tt>.
</source>
 
Return the value of the previous counter_next on $counter.
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
<!-- Edit below this comment -->
  
  
 
<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
 +
</div>
 
<!-- Pod2Wiki=item_counter_next -->
 
<!-- Pod2Wiki=item_counter_next -->
 
====counter_next====
 
====counter_next====
  
<source lang="perl">$n = $db->counter_next( $counter )
+
$n = $db-&gt;counter_next( $counter )
 
+
Return the next unused value for the named <tt>$counter</tt>. Returns <tt>undef</tt> if the <tt>$counter</tt> doesn't exist.
</source>
 
Return the next unused value for the named counter. Returns undef if the counter doesn't exist.
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
 +
</div>
 
<!-- Pod2Wiki=item_counter_minimum -->
 
<!-- Pod2Wiki=item_counter_minimum -->
 
====counter_minimum====
 
====counter_minimum====
  
<source lang="perl">$db->counter_minimum( $counter, $value )
+
$db-&gt;counter_minimum( $counter, $value )
 
+
Ensure that the <tt>$counter</tt> is set no lower than <tt>$value</tt>. This is used when importing eprints which may not be in scrict sequence.
</source>
 
Ensure that the counter is set no lower than $value. This is used when importing eprints which may not be in scrict sequence.
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
<!-- Edit below this comment -->
  
  
 
<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
 +
</div>
 
<!-- Pod2Wiki=item_counter_reset -->
 
<!-- Pod2Wiki=item_counter_reset -->
 
====counter_reset====
 
====counter_reset====
  
<source lang="perl">$db->counter_reset( $counter )
+
$db-&gt;counter_reset( $counter )
 
+
Reset the <tt>$counter</tt>. Use with caution.
</source>
 
Reset the counter. Use with caution.
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
<!-- Edit below this comment -->
  
  
 
<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
 +
</div>
 
<!-- Pod2Wiki=item_next_doc_pos -->
 
<!-- Pod2Wiki=item_next_doc_pos -->
 
====next_doc_pos====
 
====next_doc_pos====
  
<source lang="perl">$n = $db->next_doc_pos( $eprintid )
+
$n = $db-&gt;next_doc_pos( $eprintid )
 
+
Return the next unused document position for the given <tt>$eprintid</tt>.
</source>
 
Return the next unused document pos for the given eprintid.
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=head_sql_utility_methods -->
+
</div>
===SQL utility methods===
+
<!-- Pod2Wiki=head_dataset_data -->
 +
===Dataset Data===
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_do -->
+
</div>
====do====
+
<!-- Pod2Wiki=item_exists -->
 
+
====exists====
<source lang="perl">$success = $db->do( $sql )
 
  
</source>
+
$boolean = $db-&gt;exists( $dataset, $id )
Execute the given SQL.
+
Return <tt>true</tt> if there exists an [[API:EPrints/DataObj|EPrints::DataObj]] from the <tt>$dataset</tt> with its primary key set to <tt>$id</tt>. Otherwise, return  <tt>false</tt>.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_prepare -->
+
</div>
====prepare====
+
<!-- Pod2Wiki=item_add_record -->
 +
====add_record====
 +
 
 +
$success = $db-&gt;add_record( $dataset, $data )
 +
Add the given <tt>$data</tt> as a new record in the given <tt>$dataset</tt>.  <tt>$data</tt> is a reference to a hash containing values structured for a  record in the that <tt>$dataset</tt>.
 +
 
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 +
<!-- Edit below this comment -->
  
<source lang="perl">$sth = $db->prepare( $sql )
 
  
</source>
+
<!-- Pod2Wiki= -->
Prepare the SQL statement $sql for execution.
+
</div>
 +
<!-- Pod2Wiki=item_remove -->
 +
====remove====
  
Use the <tt>execute</tt> method on the returned {{API:PodLink|file=DBI|package_name=DBI|section=|text=DBI}} handle to execute the SQL:
+
$success = $db-&gt;remove( $dataset, $id )
 +
Attempts to remove the [[API:EPrints/DataObj|EPrints::DataObj]] with the primary key <tt>$id</tt> from the specified <tt>$dataset</tt>.
  
  my $sth = $db-&gt;prepare_select( "SELECT 'Hello, World'" );
+
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce; padding: 0em 1em 0em 1em; font-size: 80%; '>
  $sth-&gt;execute;
+
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_prepare_select -->
+
</div>
====prepare_select====
+
<!-- Pod2Wiki=head_searching_caching_and_object_retrieval -->
 +
===Searching, caching and object retrieval===
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 +
<!-- Edit below this comment -->
  
<source lang="perl">$sth = $db->prepare_select( $sql [, %options ] )
 
  
</source>
+
<!-- Pod2Wiki= -->
Prepare a SELECT statement $sql for execution.
+
</div>
 +
<!-- Pod2Wiki=item_cache_exp -->
 +
====cache_exp====
  
Returns a {{API:PodLink|file=DBI|package_name=DBI|section=|text=DBI}} statement handle.
+
$searchexp = $db-&gt;cache_exp( $cacheid )
 +
Return the serialised search of a the cached search with <tt>$cacheid</tt>. Return <tt>undef</tt> if the <tt>$cacheid</tt> is invalid or expired.
  
The LIMIT SQL keyword is not universally supported, to specify a LIMIT you must use the '''limit''' option.
+
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 +
<!-- Edit below this comment -->
  
Options:
 
  
  limit - limit the number of rows returned
+
<!-- Pod2Wiki= -->
  offset - return '''limit''' number of rows after offset
+
</div>
 
+
<!-- Pod2Wiki=item_cache -->
<!-- Edit below this comment -->
+
====cache====
  
 +
$cacheid = $db-&gt;cache( $searchexp, $dataset, $srctable, [$order], [$list] )
 +
Create a cache of the specified search expression from the SQL table <tt>$srctable</tt>.
  
<!-- Pod2Wiki= -->
+
If <tt>$order</tt> is set then the cache is ordered by the specified fields.  For example <tt>-year/title</tt> orders by year (descending). Records with  the same year are ordered by title.
<!-- Pod2Wiki=item_has_sequence -->
 
====has_sequence====
 
  
<source lang="perl">$boolean = $db->has_sequence( $name )
+
If <tt>$srctable</tt> is set to <tt>LIST</tt> then order is ignored and the list  of IDs is taken from the array reference <tt>$list</tt>.
  
</source>
+
If <tt>$srctable</tt> is set to <tt>ALL</tt> every matching record from $dataset  is added to the cache, optionally ordered by <tt>$order</tt>.
Return true if a sequence of the given name exists in the database.
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_create_sequence -->
+
</div>
====create_sequence====
+
<!-- Pod2Wiki=item_cache_table -->
 
+
====cache_table====
<source lang="perl">$success = $db->create_sequence( $seq_name )
 
  
</source>
+
$tablename = $db-&gt;cache_table( $id )
Creates a new sequence object initialised to zero.
+
Return the name of the SQL table used to store the cache with <tt>$id</tt>.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_drop_sequence -->
+
</div>
====drop_sequence====
+
<!-- Pod2Wiki=item_cache_userid -->
 
+
====cache_userid====
<source lang="perl">$success = $db->drop_sequence( $seq_name )
 
  
</source>
+
$userid = $db-&gt;cache_userid( $id )
Deletes a sequence object.
+
Returns the <tt>userid</tt> associated with the cache with <tt>$id</tt> if that  cache exists.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_drop_column -->
+
</div>
====drop_column====
+
<!-- Pod2Wiki=item_get_cachemap -->
 +
====get_cachemap====
  
<source lang="perl">$success = $db->drop_column( $table, $column )
+
$cachemap = $db-&gt;get_cachemap( $id )
 
+
Return the cachemap with $&lt;id&gt;.
</source>
 
Drops a column from a table.
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_get_primary_key -->
+
</div>
====get_primary_key====
+
<!-- Pod2Wiki=item_search -->
 +
====search====
  
<source lang="perl">@columns = $db->get_primary_key( $tablename )
+
$ids = $db-&gt;search( $keyfield, $tables, $conditions, [ $main_table_alias ] )
 +
Return a reference to an array of <tt>$keyfield</tt> IDs - the results of  the search specified by <tt>$conditions</tt> across the tables specified in  the <tt>$tables</tt> hash where keys are tables aliases and values are table  names.
  
</source>
+
If no <tt>$main_table_alias</tt> is specified then <tt>M</tt> is assumed.  
Returns the list of column names that comprise the primary key for $tablename.
 
 
 
Returns empty list if no primary key exists.
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_create_primary_key -->
+
</div>
====create_primary_key====
+
<!-- Pod2Wiki=item_drop_cache -->
 
+
====drop_cache====
<source lang="perl">$db->create_primary_key( $tablename, @cols )
 
  
</source>
+
$db-&gt;drop_cache( $id )
Create a PRIMARY KEY on $tablename over @cols.
+
Remove the cached search with the given <tt>$id</tt>.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_create_index -->
+
</div>
====create_index====
+
<!-- Pod2Wiki=item_from_cache -->
 +
====from_cache====
 +
 
 +
$items = $db-&gt;from_cache( $dataset, $cacheid, [ $offset, $count, $justids ] )
 +
Return a reference to an array containing all the items from the given  <tt>$dataset</tt> that have IDs in the cache specified by <tt>$cacheid</tt>. The  cache may be specified either by ID or serialised search expression.
  
<source lang="perl">$success = $db->create_index( $tablename, @columns )
+
<tt>$offset</tt> is an offset from the start of the cache and <tt>$count</tt> is  the number of records to return.
  
</source>
+
If <tt>$justids</tt> is <tt>true</tt> then it returns just a reference to an array  of the record IDs and not the objects themselves.
Creates an index over @columns for $tablename. Returns true on success.
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
<!-- Edit below this comment -->
  
  
 
<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_create_unique_index -->
+
</div>
====create_unique_index====
+
<!-- Pod2Wiki=item_drop_orphan_cache_tables -->
 
+
====drop_orphan_cache_tables====
<source lang="perl">$success = $db->create_unique_index( $tablename, @columns )
 
  
</source>
+
$c = $db-&gt;drop_orphan_cache_tables
Creates a unique index over @columns for $tablename. Returns true on success.
+
Drop tables called <tt>cacheXXX</tt> where <tt>XXX</tt> is an integer. Returns the  number of cache tables dropped.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
<!-- Edit below this comment -->
  
  
 
<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_index_name -->
+
</div>
====index_name====
+
<!-- Pod2Wiki=item_get_single -->
 
+
====get_single====
<source lang="perl">$name = $db->index_name( $table, @columns )
 
 
 
</source>
 
Returns the name of the first index that starts with @columns on the $table table.
 
  
Returns undef if no index exists.
+
$obj = $db-&gt;get_single( $dataset, $id )
 +
Return a single &lt;EPrints::DataObj&gt; from the given <tt>$dataset</tt> with primary key set to <tt>$id</tt>.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
<!-- Edit below this comment -->
  
  
 
<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item__update -->
+
</div>
====_update====
+
<!-- Pod2Wiki=item_get_all -->
 +
====get_all====
 +
 
 +
$items = $db-&gt;get_all( $dataset )
 +
Returns a reference to an array with all the &lt;EPrints::DataObj&gt;s from  the given <tt>$dataset</tt>.
  
<source lang="perl">$rows = $db->_update( $tablename, $keycols, $keyvals, $columns, @values )
+
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 +
<!-- Edit below this comment -->
  
</source>
 
UPDATES $tablename where $keycols equals $keyvals and returns the number of rows affected.
 
  
Note! If no rows are affected the result is still 'true', see DBI's execute() method.
+
<!-- Pod2Wiki= -->
 +
</div>
 +
<!-- Pod2Wiki=item_get_cache_ids -->
 +
====get_cache_ids====
  
This method is internal.
+
@ids = $db-&gt;get_cache_ids( $dataset, $cachemap, $offset, $count )
 +
Returns a list of <tt>$count</tt> IDs from <tt>$cache_id</tt> starting at  <tt>$offset</tt> and in the order in the <tt>$cachemap</tt>.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_insert -->
+
</div>
====insert====
+
<!-- Pod2Wiki=item_get_dataobjs -->
 +
====get_dataobjs====
  
<source lang="perl">$success = $db->insert( $table, $columns, @values )
+
@dataobjs = $db-&gt;get_dataobjs( $dataset, [ $id, $id, ... ] )
 
+
Retrieves the records in <tt>$dataset</tt> with the given <tt>$id</tt>(s). If an  <tt>$id</tt> doesn't exist in the database it will be ignored.
</source>
 
Inserts values into the table $table. If $columns is defined it will be used as a list of columns to insert into. @values is a list of arrays containing values to insert.
 
 
 
Values will be quoted before insertion.
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
<!-- Edit below this comment -->
 
<!-- Edit below this comment -->
  
  
 
<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_insert_quoted -->
+
</div>
====insert_quoted====
+
<!-- Pod2Wiki=item_get_values -->
 
+
====get_values====
<source lang="perl">$success = $db->insert_quoted( $table, $columns, @qvalues )
 
 
 
</source>
 
Inserts values into the table $table. If $columns is defined it will be used as a list of columns to insert into. @qvalues is a list of arrays containing values to insert.
 
  
Values will NOT be quoted before insertion - care must be exercised!
+
$values = $db-&gt;get_values( $field, $dataset )
 +
Return a reference to an array of all the distinct values of the  [[API:EPrints/MetaField|EPrints::MetaField]] <tt>$field</tt> for the <tt>$dataset</tt> specified.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_delete_from -->
+
</div>
====delete_from====
+
<!-- Pod2Wiki=item_sort_values -->
 
+
====sort_values====
<source lang="perl">$success = $db->delete_from( $table, $columns, @values )
 
  
</source>
+
$values = $db-&gt;sort_values( $field, $values, [ $langid ] )
Perform a SQL DELETE FROM $table using $columns to build a where clause. @values is a list of array references of values in the same order as $columns.
+
Sorts and returns the list of <tt>$values</tt> using the database.
  
If you want to clear a table completely use clear_table().
+
<tt>$field</tt> is used to get the order value for each value. <tt>$langid</tt>  (or $session-&gt;get_langid if unset) is used to determine the database  collation to use when sorting the resulting order values.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_count_table -->
+
</div>
====count_table====
+
<!-- Pod2Wiki=item_get_ids_by_field_values -->
 
+
====get_ids_by_field_values====
<source lang="perl">$n = $db->count_table( $tablename )
 
  
</source>
+
$ids = $db-&gt;get_ids_by_field_values( $field, $dataset, [ %opts ] )
Return the number of rows in the specified SQL table.
+
Return a reference to a hash table where the keys are specified  <tt>$datasets</tt>'s <tt>$field</tt> value IDs and the values are references to  arrays of IDs.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_has_table -->
+
</div>
====has_table====
+
<!-- Pod2Wiki=item_dequeue_events -->
 
+
====dequeue_events====
<source lang="perl">$boolean = $db->has_table( $tablename )
 
  
</source>
+
@events = $db-&gt;dequeue_events( $n )
Return true if a table of the given name exists in the database.
+
Attempt to dequeue upto <tt>$n</tt> events. May return between <tt>0</tt> and  <tt>$n</tt> events depending on parallel processes and how many events are  remaining in the queue.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_has_column -->
+
</div>
====has_column====
+
<!-- Pod2Wiki=item_ci_lookup -->
 +
====ci_lookup====
 +
 
 +
$value = $db-&gt;ci_lookup( $field, $value )
 +
This is a hacky method to support case-insensitive lookup for usernames, emails, etc.  It returns the actual case-sensitive version of <tt>$value</tt> if there is a case-insensitive match for the <tt>$field</tt>.
  
<source lang="perl">$boolean = $db->has_column( $tablename, $columnname )
+
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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 +
<!-- Edit below this comment -->
  
</source>
 
Return true if the a table of the given name has a column named $columnname in the database.
 
  
 +
<!-- Pod2Wiki= -->
 +
</div>
 +
<!-- Pod2Wiki=head_password_validation_and_secret_fields -->
 +
===Password Validation and Secret Fields===
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_drop_table -->
+
</div>
====drop_table====
+
<!-- Pod2Wiki=item_valid_login -->
 +
====valid_login====
  
<source lang="perl">$db->drop_table( $tablename [, $tablename2 ] )
+
$db-&gt;valid_login( $username, $password )
 
+
Returns whether the clear-text <tt>$password</tt> matches the stored crypted  password for the <tt>$username</tt>.
</source>
 
Delete the named table(s). Use with caution!
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_clear_table -->
+
</div>
====clear_table====
+
<!-- Pod2Wiki=item_secret_matches -->
 +
====secret_matches====
  
<source lang="perl">$db->clear_table( $tablename )
+
$db-&gt;secret_matches( $dataobj, $fieldname, $token [, $callback ] )
 +
Returns whether the clear-text <tt>$token</tt> matches the stored crypted  field with <tt>$fieldname</tt> for the <tt>$dataobj</tt> according to the  <tt>$callback</tt> function.
  
</source>
+
If not set, <tt>$callback</tt> defaults to [[API:EPrints/Utils#crypt_equals|EPrints::Utils#crypt_equals]].
Clears all records from the given table, use with caution!
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_rename_table -->
+
</div>
====rename_table====
+
<!-- Pod2Wiki=item_is_secret_set -->
 +
====is_secret_set====
 +
 
 +
$boolean = $db-&gt;is_secret_set( $dataobj, $fieldname )
 +
Returns a boolean for whether the secret <tt>$fieldname</tt> for <tt>$dataobj</tt>  has a value set.
  
<source lang="perl">$db->rename_table( $tablename, $newtablename )
+
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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 +
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</source>
 
Renames the table from the old name to the new one.
 
  
 +
<!-- Pod2Wiki= -->
 +
</div>
 +
<!-- Pod2Wiki=head_database_schema_manipulation -->
 +
===Database Schema Manipulation===
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_swap_table -->
+
</div>
====swap_table====
+
<!-- Pod2Wiki=item_has_sequence -->
 
+
====has_sequence====
<source lang="perl">$db->swap_table( $table_a, $table_b )
 
  
</source>
+
$boolean = $db-&gt;has_sequence( $name )
Swap table a and table b.  
+
Returns <tt>true</tt> if a sequence of the given <tt>$name</tt> exists in the  database. Otherwise, returns <tt>false</tt>.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_get_tables -->
+
</div>
====get_tables====
+
<!-- Pod2Wiki=item_create_sequence -->
 +
====create_sequence====
  
<source lang="perl">@tables = $db->get_tables
+
$success = $db-&gt;create_sequence( $name )
 
+
Creates a new sequence object with <tt>$name</tt> and initialises to zero.
</source>
 
Return a list of all the tables in the database.
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=head_quoting_values -->
+
</div>
===Quoting Values===
+
<!-- Pod2Wiki=item_drop_sequence -->
 +
====drop_sequence====
 +
 
 +
$success = $db-&gt;drop_sequence( $name )
 +
Deletes a sequence object with <tt>$name</tt>.
 +
 
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_prep_int -->
+
</div>
====prep_int====
+
<!-- Pod2Wiki=item_has_column -->
 +
====has_column====
  
<source lang="perl">$mungedvalue = EPrints::Database::prep_int( $value )
+
$boolean = $db-&gt;has_column( $table, $column )
 
+
Return <tt>true</tt> if the named <tt>$table</tt> has the named <tt>$column</tt> in the  database.
</source>
 
Escape a numerical value for SQL. undef becomes NULL. Anything else becomes a number (zero if needed).
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_prep_value -->
+
</div>
====prep_value====
+
<!-- Pod2Wiki=item_drop_column -->
 +
====drop_column====
  
<source lang="perl">$mungedvalue = EPrints::Database::prep_value( $value )
+
$success = $db-&gt;drop_column( $table, $column )
 
+
Drops the named <tt>$column</tt> from the named <tt>$table</tt>.
</source>
 
Escape a value for SQL. Modify value such that " becomes \" and \  becomes \\ and ' becomes \'
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_prep_like_value -->
+
</div>
====prep_like_value====
+
<!-- Pod2Wiki=item_get_primary_key -->
 +
====get_primary_key====
  
<source lang="perl">$mungedvalue = EPrints::Database::prep_like_value( $value )
+
@columns = $db-&gt;get_primary_key( $tablename )
 +
Returns a list of column names that comprise the primary key for  the <tt>$tablename</tt>.
  
</source>
+
Returns an empty list if no primary key exists.
Escape an value for an SQL like field. In addition to ' " and \ also  escapes % and _
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_quote_value -->
+
</div>
====quote_value====
+
<!-- Pod2Wiki=item_index_name -->
 +
====index_name====
  
<source lang="perl">$str = $db->quote_value( $value )
+
$name = $db-&gt;index_name( $table, @cols )
 +
Returns the name of the first index that starts with named columns  <tt>@cols</tt> in the named <tt>$table</tt>.
  
</source>
+
Returns <tt>undef</tt> if no index exists.
Return a quoted value. To quote a 'like' value you should do:
 
  
my $str = $database-&gt;quote_value( EPrints::Database::prep_like_value( $foo ) . '%' );
+
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 
+
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_quote_int -->
+
</div>
====quote_int====
+
<!-- Pod2Wiki=item_get_index_ids -->
 
+
====get_index_ids====
<source lang="perl">$str = $db->quote_int( $value )
 
  
</source>
+
$ids = $db-&gt;get_index_ids( $table, $condition )
Return a quoted integer value
+
Return a reference to an array of the distinct primary keys from the named SQL <tt>$table</tt> which match the specified <tt>$condition</tt>.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_quote_binary -->
+
</div>
====quote_binary====
+
<!-- Pod2Wiki=item_create_index -->
 +
====create_index====
  
<source lang="perl">$str = $db->quote_binary( $bytes )
+
$success = $db-&gt;create_index( $table, @columns )
 
+
Creates an index over <tt>@columns</tt> for named <tt>$table</tt>. Returns <tt>true</tt>  on success, <tt>false</tt> otherwise.
</source>
 
Some databases (Oracle/PostgreSQL) require transforms of binary data to work correctly.
 
 
 
This method should be called on data containing nul bytes or back-slashes before being passed on [[API:EPrints/Database#quote_value|quote_value]].
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_quote_ordervalue -->
+
</div>
====quote_ordervalue====
+
<!-- Pod2Wiki=item_create_unique_index -->
 
+
====create_unique_index====
<source lang="perl">$str = $db->quote_ordervalue( $field, $value )
 
  
</source>
+
$success = $db-&gt;create_unique_index( $tablename, @columns )
Some databases (Oracle) can't order by CLOBS so need special treatment when creating the ordervalues tables. This method allows any fixing-up required for string data before it's inserted.
+
Creates a unique index over <tt>@columns</tt> for named <tt>$table</tt>. Returns  <tt>true</tt> on success, <tt>false</tt> otherwise.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_quote_identifier -->
+
</div>
====quote_identifier====
+
<!-- Pod2Wiki=item_create_foreign_key -->
 +
====create_foreign_key====
  
<source lang="perl">$str = $db->quote_identifier( @parts )
+
$ok = $db-&gt;create_foreign_key( $main_table, $table, $key_field )
 +
Create a foreign key relationship between named <tt>$main_table</tt> and  named <tt>$table</tt> using <tt>$key_field</tt>.
  
</source>
+
This will cause records in <tt>$table</tt> to be deleted if the equivalent  record is deleted from <tt>$main_table</tt>.
Quote a database identifier (e.g. table names). Multiple @parts will be joined by dot.
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
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<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_prepare_regexp -->
+
</div>
====prepare_regexp====
+
<!-- Pod2Wiki=item_get_tables -->
 +
====get_tables====
  
<source lang="perl">$sql = $db->prepare_regexp( $quoted_column, $quoted_value )
+
@tables = $db-&gt;get_tables( [ $dbname ] )
 +
Returns a list of all the tables in the database. 
  
</source>
+
<tt>$dbname</tt> specifies a particular database name of current connection has access to more than one database.
The syntax used for regular expressions varies across databases. This method takes two '''quoted''' values and returns a SQL expression that will apply the regexp ($quoted_value) to the column ($quoted_column).
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_sql_as -->
+
</div>
====sql_as====
+
<!-- Pod2Wiki=item_has_table -->
 
+
====has_table====
<source lang="perl">$sql = $db->sql_AS()
 
  
</source>
+
$boolean = $db-&gt;has_table( $tablename )
Returns the syntactic glue to use when aliasing. SQL 92 DBs will happilly use " AS " but some DBs (Oracle!) won't accept it.
+
Returns boolean dependent on whether a table of the <tt>$tablename</tt> exists in the database.
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_sql_like -->
+
</div>
====sql_like====
+
<!-- Pod2Wiki=item_create_table -->
 +
====create_table====
  
<source lang="perl">$sql = $db->sql_LIKE()
+
$success = $db-&gt;create_table( $tablename, $setkey, @fields );
 +
Creates a new table with <tt>$tablename</tt> based on <tt>@fields</tt>.
  
</source>
+
The first <tt>$setkey</tt> number of fields are used for its primary key.
Returns the syntactic glue to use when making a case-insensitive LIKE. PostgreSQL requires "ILIKE" while everything else uses "LIKE" and the column collation.
 
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=head_dataset_data -->
+
</div>
===Dataset Data===
+
<!-- Pod2Wiki=item_drop_table -->
 +
====drop_table====
 +
 
 +
$db-&gt;drop_table( @tables )
 +
Delete the named <tt>@tables</tt>. Use with caution!
 +
 
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_insert_data -->
+
</div>
====insert_data====
+
<!-- Pod2Wiki=item_rename_table -->
 +
====rename_table====
 +
 
 +
$db-&gt;rename_table( $table_from, $table_to )
 +
Renames the table named <tt>$table_from</tt> to <tt>$table_to</tt>.
  
<source lang="perl">$success = $db->insert_data( $dataset, $data )
+
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
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 +
<!-- Edit below this comment -->
  
</source>
 
Add the given data as a new record in the given dataset. $data is a reference to a hash containing values structured for a record in the that dataset.
 
  
Returns undef if a record already exists with the key field value in $data.
+
<!-- Pod2Wiki= -->
 +
</div>
 +
<!-- Pod2Wiki=item_swap_table -->
 +
====swap_table====
  
Inserts ordervalues if the dataset is {{API:PodLink|file=EPrints/DataSet|package_name=EPrints::DataSet|section=ordered|text=ordered}}.
+
$db-&gt;swap_table( $table_a, $table_b )
 +
Renames table named <tt>$table_a</tt> to <tt>$table_b</tt> and vice-versa.  
  
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_update_data -->
+
</div>
====update_data====
+
<!-- Pod2Wiki=head_eprints_schema_manipulation -->
 +
===EPrints Schema Manipulation===
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 +
<span style='display:none'>User Comments</span>
 +
<!-- Edit below this comment -->
  
<source lang="perl">$success = $db->update_data( $dataset, $data, $changed )
 
  
</source>
+
<!-- Pod2Wiki= -->
Updates a record in the given {{API:PodLink|file=EPrints/DataSet|package_name=EPrints::DataSet|section=|text=$dataset}}. $data is a copy of the entire record's data and $changed the values that have changed.
+
</div>
 
+
<!-- Pod2Wiki=item_create_archive_tables -->
If the record does not already exist or the key field is unset in $data no changes will be written.
+
====create_archive_tables====
  
Updates ordervalues if the dataset is {{API:PodLink|file=EPrints/DataSet|package_name=EPrints::DataSet|section=ordered|text=ordered}}.
+
$success = $db-&gt;create_archive_tables()
 +
Create all the SQL tables for all datasets.
  
 +
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 +
<span style='display:none'>User Comments</span>
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_exists -->
+
</div>
====exists====
+
<!-- Pod2Wiki=item_drop_archive_tables -->
 
+
====drop_archive_tables====
<source lang="perl">$boolean = $db->exists( $dataset, $id )
 
  
</source>
+
$db-&gt;drop_archive_tables()
Return true if a record with the given primary key exists in the dataset, otherwise false.
+
Destroy all tables used by EPrints in the database.
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_remove -->
+
</div>
====remove====
+
<!-- Pod2Wiki=item_create_version_table -->
 +
====create_version_table====
  
<source lang="perl">$success = $db->remove( $dataset, $id )
+
$db-&gt;create_version_table
 +
Make the version table (and set the only value to be the current version of EPrints).
  
</source>
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<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
Remove the record, index terms and order value with the key field value $id from the specified dataset.
+
<span style='display:none'>User Comments</span>
 +
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Returns true on success.
 
  
<!-- Edit below this comment -->
+
<!-- Pod2Wiki= -->
 +
</div>
 +
<!-- Pod2Wiki=item_drop_version_table -->
 +
====drop_version_table====
  
 +
$db-&gt;drop_version_table
 +
Drop the version table.
  
<!-- Pod2Wiki= -->
+
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<!-- Pod2Wiki=head_searching_caching_and_retrieval -->
+
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===Searching, Caching and Retrieval===
 
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_cache_exp -->
+
</div>
====cache_exp====
+
<!-- Pod2Wiki=item_has_dataset -->
 +
====has_dataset====
  
<source lang="perl">$searchexp = $db->cache_exp( $cacheid )
+
$db-&gt;has_dataset( $dataset )
 +
Returns <tt>true</tt> if <tt>$dataset</tt> exists in the database and has all  expected tables including ordervalues and index tables.
  
</source>
+
This does not check that all fields are configured - see &lt;/has_field&gt;.
Return the serialised Search of a the cached search with id $cacheid. Return undef if the id is invalid or expired.
 
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_cache -->
+
</div>
====cache====
+
<!-- Pod2Wiki=item_has_dataset_index_tables -->
 +
====has_dataset_index_tables====
  
<source lang="perl">$cacheid = $db->cache( $searchexp, $dataset, $srctable, [$order], [$list] )
+
$db-&gt;has_dataset_index_tables( $dataset )
 +
Returns <tt>true</tt> if index tables for <tt>$dataset</tt> exists of if this is  not indexable.
  
</source>
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Create a cache of the specified search expression from the SQL table $srctable.
+
<span style='display:none'>User Comments</span>
 +
<!-- Edit below this comment -->
  
If $order is set then the cache is ordered by the specified fields. For example "-year/title" orders by year (descending). Records with the same year are ordered by title.
 
  
If $srctable is set to "LIST" then order is ignored and the list of ids is taken from the array reference $list.
+
<!-- Pod2Wiki= -->
 +
</div>
 +
<!-- Pod2Wiki=item_create_dataset_tables -->
 +
====create_dataset_tables====
  
If $srctable is set to "ALL" every matching record from $dataset is added to the cache, optionally ordered by $order.
+
$success = $db-&gt;create_dataset_tables( $dataset )
 +
Creates all the SQL tables for the specified <tt>$dataset</tt>.
  
 +
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 +
<span style='display:none'>User Comments</span>
 
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_cache_table -->
+
</div>
====cache_table====
+
<!-- Pod2Wiki=item_drop_dataset_tables -->
 +
====drop_dataset_tables====
  
<source lang="perl">$tablename = $db->cache_table( $id )
+
$db-&gt;drop_dataset_tables( $dataset )
 
+
Drops all the SQL tables for the specified <tt>$dataset</tt>.
</source>
 
Return the SQL table used to store the cache with id $id.
 
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_search -->
+
</div>
====search====
+
<!-- Pod2Wiki=item_create_dataset_index_tables -->
 +
====create_dataset_index_tables====
 +
 
 +
$success = $db-&gt;create_dataset_index_tables( $dataset )
 +
Creates all the index tables for the specified <tt>$dataset</tt>.
 +
 
 +
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<!-- Edit below this comment -->
  
<source lang="perl">$ids = $db->search( $keyfield, $tables, $conditions, [$main_table_alias] )
 
  
</source>
+
<!-- Pod2Wiki= -->
Return a reference to an array of ids - the results of the search specified by $conditions accross the tables specified in the $tables hash where keys are tables aliases and values are table names.
+
</div>
 +
<!-- Pod2Wiki=item_create_dataset_ordervalues_tables -->
 +
====create_dataset_ordervalues_tables====
  
If no table alias is passed then M is assumed.  
+
$success = $db-&gt;create_dataset_ordervalues_tables( $dataset )
 +
Creates all the ordervalues tables for the specified <tt>$dataset</tt>.
  
 +
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+
</div>
====drop_cache====
+
<!-- Pod2Wiki=item_has_field -->
 
+
====has_field====
<source lang="perl">$db->drop_cache( $id )
 
  
</source>
+
$db-&gt;has_field( $dataset, $field )
Remove the cached search with the given id.
+
Returns <tt>true</tt> if <tt>$field</tt> is in the database for <tt>$dataset</tt>.
  
 +
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<!-- Pod2Wiki=item_from_cache -->
+
</div>
====from_cache====
+
<!-- Pod2Wiki=item_add_field -->
 
+
====add_field====
<source lang="perl">$foo = $db->from_cache( $dataset, $cacheid, [$offset], [$count], [$justids] )
 
 
 
</source>
 
Return a reference to an array containing all the items from the given dataset that have id's in the specified cache. The cache may be  specified either by id or serialised search expression.
 
  
$offset is an offset from the start of the cache and $count is the number of records to return.
+
$db-&gt;add_field( $dataset, $field, [ $force ] )
 +
Add <tt>$field</tt> to <tt>$dataset</tt>'s tables.
  
If $justids is true then it returns just an ref to an array of the record ids, not the objects.
+
If <tt>$force</tt> is <tt>true</tt> modify/replace an existing column. Use with  care!
  
 +
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+
</div>
====drop_orphan_cache_tables====
+
<!-- Pod2Wiki=item_remove_field -->
 
+
====remove_field====
<source lang="perl">$c = $db->drop_orphan_cache_tables
 
  
</source>
+
$db-&gt;remove_field( $dataset, $field )
Drop tables called "cacheXXX" where XXX is an integer. Returns the number of tables dropped.
+
Remove <tt>$field</tt> from <tt>$dataset</tt>'s tables.
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_get_single -->
+
</div>
====get_single====
+
<!-- Pod2Wiki=item_rename_field -->
 +
====rename_field====
  
<source lang="perl">$obj = $db->get_single( $dataset, $id )
+
$ok = $db-&gt;rename_field( $dataset, $field, $old_name )
 +
Rename the <tt>$field</tt> in the <tt>$dataset</tt> from its <tt>$old_name</tt>.
  
</source>
+
Returns <tt>true</tt> if the <tt>$field</tt> is successfully renamed.
Return a single item from the given dataset. The one with the specified id.
 
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_get_all -->
+
</div>
====get_all====
+
<!-- Pod2Wiki=item_create_counters -->
 +
====create_counters====
  
<source lang="perl">$items = $db->get_all( $dataset )
+
$success = $db-&gt;create_counters
 
+
Create the counters used to store the highest current ID of eprints, users, etc.
</source>
 
Returns a reference to an array with all the items from the given dataset.
 
  
 +
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<!-- Pod2Wiki=item_get_cache_ids -->
+
</div>
====get_cache_ids====
+
<!-- Pod2Wiki=item_has_counter -->
 
+
====has_counter====
<source lang="perl">@ids = $db->get_cache_ids( $dataset, $cachemap, $offset, $count )
 
  
</source>
+
$success = $db-&gt;has_counter( $counter )
Returns a list of $count ids from $cache_id starting at $offset and in the order in the cachemap.
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Returns <tt>true</tt> if <tt>$counter</tt> exists.
  
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<!-- Pod2Wiki= -->
 
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<!-- Pod2Wiki=item_get_dataobjs -->
+
</div>
====get_dataobjs====
+
<!-- Pod2Wiki=item_create_counter -->
 
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====create_counter====
<source lang="perl">@dataobjs = $db->get_dataobjs( $dataset [, $id [, $id ] ] )
 
  
</source>
+
$success = $db-&gt;create_counter( $name )
Retrieves the records in $dataset with the given $id(s). If an $id doesn't exist in the database it will be ignored.
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Create and initialise to zero a new counter with <tt>$name</tt>.
  
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+
</div>
====get_values====
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<!-- Pod2Wiki=item_remove_counters -->
 +
====remove_counters====
  
<source lang="perl">$foo = $db->get_values( $field, $dataset )
+
$success = $db-&gt;remove_counters
 
+
Destroy all counters.
</source>
 
Return a reference to an array of all the distinct values of the  [[API:EPrints/MetaField|EPrints::MetaField]] specified.
 
  
 +
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+
</div>
====get_ids_by_field_values====
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<!-- Pod2Wiki=item_drop_counter -->
 +
====drop_counter====
 +
 
 +
$success = $db-&gt;drop_counter( $name )
 +
Destroy the counter named <tt>$name</tt>.
  
<source lang="perl">$ids = $db->get_ids_by_field_values( $field, $dataset [ %opts ] )
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<!-- Edit below this comment -->
  
</source>
 
Return a reference to a hash table where the keys are field value ids and the value is a reference to an array of ids.
 
  
 +
<!-- Pod2Wiki= -->
 +
</div>
 +
<!-- Pod2Wiki=head_user_messages -->
 +
===User Messages===
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=item_dequeue_events -->
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</div>
====dequeue_events====
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<!-- Pod2Wiki=item_save_user_message -->
 +
====save_user_message====
  
<source lang="perl">@events = $db->dequeue_events( $n )
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$message = $db-&gt;save_user_message( $userid, $m_type, $dom_m_data )
 
+
Save user message provided in XML DOM object <tt>$dom_m_data</tt> as a  sanitized string in a [[API:EPrints:DataObj/Message|EPrints:DataObj::Message]] using <tt>$m_type</tt> to define the message type and <tt>$userid</tt> for the ID of the user whose message it is.
</source>
 
Attempt to dequeue upto $n events. May return between 0 and $n events depending on parallel processes and how many events are remaining on the queue.
 
  
 +
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+
</div>
===Password Validation===
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<!-- Pod2Wiki=item_get_user_messages -->
 +
====get_user_messages====
 +
 
 +
@messages = $db-&gt;get_user_messages( $userid, %opts )
 +
Get the messages for a user with ID <tt>$userid</tt> and clear messages if <tt>$opt{clear}</tt> is set.
 +
 
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</div>
====valid_login====
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<!-- Pod2Wiki=item_clear_user_messages -->
 +
====clear_user_messages====
  
<source lang="perl">$real_username = $db->valid_login( $username, $password )
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$db-&gt;clear_user_messages( $userid )
 
+
Clear all messages for user with ID <tt>$userid</tt>.
</source>
 
Tests whether the clear-text $password matches the stored encrypted password for $username.
 
 
 
Returns the user's real (case-sensitive) username or undef if the passwords don't match.
 
  
 +
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</div>
 
<!-- Pod2Wiki=head_see_also -->
 
<!-- Pod2Wiki=head_see_also -->
 
==SEE ALSO==
 
==SEE ALSO==
To access database-stored objects use the methods provided by the following modules: [[API:EPrints/Repository|EPrints::Repository]], [[API:EPrints/DataSet|EPrints::DataSet]].
+
To access database-stored objects use the methods provided by the following modules: [[API:EPrints/Repository|EPrints::Repository]], [[API:EPrints/DataSet|EPrints::DataSet]].
  
 +
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
 +
</div>
 
<!-- Pod2Wiki=head_copyright -->
 
<!-- Pod2Wiki=head_copyright -->
 
==COPYRIGHT==
 
==COPYRIGHT==
 +
{{API:Copyright}}
 +
<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
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<!-- Pod2Wiki= -->
 
<!-- Pod2Wiki= -->
<!-- Pod2Wiki=_postamble_ -->
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</div>
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<!-- Pod2Wiki=_postamble_ --><!-- Edit below this comment -->
<comments />
 

Latest revision as of 23:41, 11 January 2022

EPrints 3 Reference: Directory Structure - Metadata Fields - Repository Configuration - XML Config Files - XML Export Format - EPrints data structure - Core API - Data Objects


API: Core API

Latest Source Code (3.4, 3.3) | Revision Log | Before editing this page please read Pod2Wiki


Contents

NAME

EPrints::Database - a connection to the SQL database for an eprints session.

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DESCRIPTION

EPrints Database Access Module

Provides access to the backend database. All database access done via this module, in the hope that the backend can be replaced as easily as possible.

In most use-cases it should not be necessary to use the database module directly. Instead you should use EPrints::DataSet or EPrints::MetaField accessor methods to access objects and field values respectively.

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Cross-database Support

Any use of SQL statements must use quote_identifier to quote database tables and columns and quote_value to quote values. The only exception to this are the EPrints::Database::* modules which provide database-driver specific extensions.

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Quoting SQL Values

By convention variables that contain already quoted values are prefixed with Q_ so they can be easily recognised when used in string interpolation:

my $Q_value = $db->quote_value( "Hello, World!" );
$db->do("SELECT $Q_value");
 

Where possible you should avoid quoting values yourself, instead use a method that accepts unquoted values which will (safely) do the work for you.

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CONSTANTS

All the SQL_ column types defined by Perl module DBI and the following:

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SQL_NULL

A column value is undefined.

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SQL_NOT_NULL

A column value is defined.

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INSTANCE VARIABLES

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$self->{session}

The EPrints::Session which is associated with this database connection.

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$self->{debug}

If true then SQL is logged.

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$self->{dbh}

The handle on the actual database connection.

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METHODS

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Database

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new

$db = EPrints::Database->new( $repo, [ %opts ] )

Create a connection to the database.

Options:

 db_connect - Boolean. Also connect to the database (default: true).

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create

$db = $db->create( $username, $password )

Create and connect to a new database using user account $username and $password.

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build_connection_string

$dbstr = EPrints::Database::build_connection_string( %params )

Build the string to use to connect to the database via DBI.

Parameters:

dbname - Database name (REQUIRED).
dbdriver - Database driver (e.g. mysql, Oracle, pgsql, default: mysql).
dbhost - Database host.  Assumes localhost if unset.
dbport - Port to connect to database host.  Assumes default for driver if unset.
dbsock - Socket file to connect to database through.

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connect

$db->connect()

Connects to the database.

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disconnect

$db->disconnect()

Disconnects from the EPrints database. Should always be done before any script exits.

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set_debug

$db->set_debug( $boolean )

Set the SQL debug mode to true or false.

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set_version

$db->set_version( $versionid );

Set the version id table in the SQL database to the given versionid (used by the upgrade script).

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get_version

$version = $db->get_version

Returns the current database schema version.

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is_latest_version

$boolean = $db->is_latest_version

Return true if the SQL tables are in the correct configuration for this edition of eprints. Otherwise, false.

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get_server_version

$version = $db->get_server_version

Return the database server version.

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get_default_charset

$charset = $db->get_default_charset

Return the character set to use.

Returns undef if character sets are unsupported.

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get_default_collation

$collation = $db->get_default_collation( $lang )

Return the collation to use for language $lang.

Returns undef if collation is unsupported.

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get_driver_name

$driver = $db->get_driver_name

Return the database driver name.

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error

$errstr = $db->error()

Return a string describing the last SQL error.

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retry_error

$boolean = $db->retry_error()

Returns a boolean for whether the database error is a retry error.

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duplicate_error

$boolean = $db->duplicate_error()

Returns a boolean for whether the database error is a duplicate error.

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begin

$db->begin()

Begin a transaction.

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commit

$db->commit()

Commit the previously begun transaction.

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rollback

$db->rollback()

Rollback the partially completed transaction.

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type_info

$type_info = $db->type_info( $data_type )

See DBI/type_info.

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get_column_type

$real_type = $db->get_column_type( $name, $data_type, $not_null, [ $length, $scale, %opts ] )

Returns a SQL column definition for $name of type $type, usually something like:

 $name $type($length,$scale) [ NOT NULL ]
 

If $not_null is true column will be set to NOT NULL.

$length and $scale control the maximum lengths of character or decimal types (see below).

Other options available to refine the column definition:

 langid - character set/collation to use
 sorted - whether this column will be used to order by
 

langid is mapped to real database values by the "dblanguages" configuration option. The database may not be able to order the request column type in which case, if sorted is true, the database may use a substitute column type.

$data_type is the SQL type. The types are constants defined by this module, to import them use:

 use EPrints::Database qw( :sql_types );
 

Supported types (n = requires $length argument):

Character data: SQL_VARCHAR(n), SQL_LONGVARCHAR, SQL_CLOB.

Binary data: SQL_VARBINARY(n), SQL_LONGVARBINARY.

Integer data: SQL_TINYINT, SQL_SMALLINT, SQL_INTEGER, SQL_BIGINT.

Floating-point data: SQL_REAL, SQL_DOUBLE.

Time data: SQL_DATE, SQL_TIME.

The actual column types used will be database-specific.

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Basic SQL Operations

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do

$success = $db->do( $sql )

Execute the given $sql.

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prepare

$sth = $db->prepare( $sql )

Prepare the given $sql and return a handle on it.

Use the execute method on the returned DBI handle to execute the SQL:

 my $sth = $db->prepare_select( "SELECT 'Hello, World'" );
 $sth->execute;
 

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prepare_select

$sth = $db->prepare_select( $sql, [ %options ] )

Prepare a SELECT statement $sql and return a handle to it. After preparing a statement use execute() to execute it.

Returns a DBI statement handle.

The LIMIT SQL keyword is not universally supported, to specify this use the limit option.

Options:

 limit - limit the number of rows returned
 offset - return limit number of rows after offset
 

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execute

$success = $db->execute( $sth, $sql )

Execute the SQL prepared earlier in the $sth. $sql is only required for debugging purposes.

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update

$success = $db->update( $dataset, $data, $changed )

Updates a EPrints::DataObj from $dataset with the given $data. The primary key field (e.g. eprintid) value must be included.

Updates the ordervalues if the $dataset is ordered.

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_update

$rows = $db->_update( $tablename, $keycols, $keyvals, $columns, @values )

Updates $columns in $tablename with @values where $keycols equals $keyvals and returns the number of rows affected.

N.B. If no rows are affected, the result is still true, see DBI's execute() method.

This is an internal method.

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insert

$success = $db->insert( $table, $columns, @values )

Inserts @values into the table $table. If $columns is defined it will be used as a list of columns to insert into. @values is a list of arrays containing values to insert. These will be quoted before insertion.

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insert_quoted

$success = $db->insert_quoted( $table, $columns, @qvalues )

Inserts values into the table $table. If $columns is defined it will be used as a list of columns to insert into. @qvalues is a list of arrays containing values to insert. These will NOT be quoted before insertion - care must be exercised!

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delete_from

$success = $db->delete_from( $table, $columns, @values )

Perform a SQL DELETE FROM $table using $columns to build a where clause. @values is a list of array references of values in the same order as $columns.

If you want to clear a table completely use clear_table().

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count_table

$n = $db->count_table( $tablename )

Return the number of rows in the specified SQL table with $tablename.

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clear_table

$db->clear_table( $tablename )

Clears all records from the given table with $tablename. Use with caution!

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Quoting

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prep_int

$mungedvalue = EPrints::Database::prep_int( $value )

Escape numerical $value for an SQL statement. undef becomes NULL. Anything else becomes a number (zero if needed).

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prep_value

$mungedvalue = EPrints::Database::prep_value( $value )

Escape $value for an SQL statement. Modify value such that " becomes \" and \ becomes \\ and ' becomes \'.

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prep_like_value

$mungedvalue = EPrints::Database::prep_like_value( $value )

Escape $value for an SQL LIKE clause. In addition to ' " and \ also escapes % and _.

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quote_value

$str = $db->quote_value( $value )

Return a quoted version of $value. To quote a LIKE value you should use:

$db->quote_value( EPrints::Database::prep_like_value( $foo ) . '%' );
 

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quote_int

$str = $db->quote_int( $value )

Return a quoted integer for $value.

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quote_binary

$str = $db->quote_binary( $bytes )

Some databases (Oracle/PostgreSQL) require transforms of binary data to work correctly.

This method should be called on data $bytes containing null bytes or back-slashes before being passed on quote_value.

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quote_ordervalue

$str = $db->quote_ordervalue( $field, $value )

Some databases (Oracle) can't order by CLOBs so need special treatment when creating the ordervalues tables. This method allows any fixing-up required for string data $value for $field before it's inserted.

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quote_identifier

$str = $db->quote_identifier( @parts )

Quote a database identifier (e.g. table names). Multiple @parts will be joined by dots (.).

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prepare_regexp

$sql = $db->prepare_regexp( $col, $value )

The syntax used for regular expressions varies across databases. This method takes two quoted string and returns a SQL expression that will apply the quoted regexp $value to the quoted column $col.

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sql_as

$sql = $db->sql_AS()

Returns the syntactic glue to use when aliasing. SQL 92 databases will happily use AS but some databases (Oracle) will not accept it.

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sql_like

$sql = $db->sql_LIKE()

Returns the syntactic glue to use when making a case-insensitive LIKE. PostgreSQL requires ILIKE while everything else uses LIKE and the column collation.

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Counters

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counter_current

$n = $db->counter_current( $counter )

Return the value of the previous counter_next on $counter.

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counter_next

$n = $db->counter_next( $counter )

Return the next unused value for the named $counter. Returns undef if the $counter doesn't exist.

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counter_minimum

$db->counter_minimum( $counter, $value )

Ensure that the $counter is set no lower than $value. This is used when importing eprints which may not be in scrict sequence.

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counter_reset

$db->counter_reset( $counter )

Reset the $counter. Use with caution.

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next_doc_pos

$n = $db->next_doc_pos( $eprintid )

Return the next unused document position for the given $eprintid.

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Dataset Data

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exists

$boolean = $db->exists( $dataset, $id )

Return true if there exists an EPrints::DataObj from the $dataset with its primary key set to $id. Otherwise, return false.

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add_record

$success = $db->add_record( $dataset, $data )

Add the given $data as a new record in the given $dataset. $data is a reference to a hash containing values structured for a record in the that $dataset.

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remove

$success = $db->remove( $dataset, $id )

Attempts to remove the EPrints::DataObj with the primary key $id from the specified $dataset.

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Searching, caching and object retrieval

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cache_exp

$searchexp = $db->cache_exp( $cacheid )

Return the serialised search of a the cached search with $cacheid. Return undef if the $cacheid is invalid or expired.

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cache

$cacheid = $db->cache( $searchexp, $dataset, $srctable, [$order], [$list] )

Create a cache of the specified search expression from the SQL table $srctable.

If $order is set then the cache is ordered by the specified fields. For example -year/title orders by year (descending). Records with the same year are ordered by title.

If $srctable is set to LIST then order is ignored and the list of IDs is taken from the array reference $list.

If $srctable is set to ALL every matching record from $dataset is added to the cache, optionally ordered by $order.

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cache_table

$tablename = $db->cache_table( $id )

Return the name of the SQL table used to store the cache with $id.

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cache_userid

$userid = $db->cache_userid( $id )

Returns the userid associated with the cache with $id if that cache exists.

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get_cachemap

$cachemap = $db->get_cachemap( $id )

Return the cachemap with $<id>.

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search

$ids = $db->search( $keyfield, $tables, $conditions, [ $main_table_alias ] )

Return a reference to an array of $keyfield IDs - the results of the search specified by $conditions across the tables specified in the $tables hash where keys are tables aliases and values are table names.

If no $main_table_alias is specified then M is assumed.

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drop_cache

$db->drop_cache( $id )

Remove the cached search with the given $id.

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from_cache

$items = $db->from_cache( $dataset, $cacheid, [ $offset, $count, $justids ] )

Return a reference to an array containing all the items from the given $dataset that have IDs in the cache specified by $cacheid. The cache may be specified either by ID or serialised search expression.

$offset is an offset from the start of the cache and $count is the number of records to return.

If $justids is true then it returns just a reference to an array of the record IDs and not the objects themselves.

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drop_orphan_cache_tables

$c = $db->drop_orphan_cache_tables

Drop tables called cacheXXX where XXX is an integer. Returns the number of cache tables dropped.

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get_single

$obj = $db->get_single( $dataset, $id )

Return a single <EPrints::DataObj> from the given $dataset with primary key set to $id.

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get_all

$items = $db->get_all( $dataset )

Returns a reference to an array with all the <EPrints::DataObj>s from the given $dataset.

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get_cache_ids

@ids = $db->get_cache_ids( $dataset, $cachemap, $offset, $count )

Returns a list of $count IDs from $cache_id starting at $offset and in the order in the $cachemap.

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get_dataobjs

@dataobjs = $db->get_dataobjs( $dataset, [ $id, $id, ... ] )

Retrieves the records in $dataset with the given $id(s). If an $id doesn't exist in the database it will be ignored.

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get_values

$values = $db->get_values( $field, $dataset )

Return a reference to an array of all the distinct values of the EPrints::MetaField $field for the $dataset specified.

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sort_values

$values = $db->sort_values( $field, $values, [ $langid ] )

Sorts and returns the list of $values using the database.

$field is used to get the order value for each value. $langid (or $session->get_langid if unset) is used to determine the database collation to use when sorting the resulting order values.

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get_ids_by_field_values

$ids = $db->get_ids_by_field_values( $field, $dataset, [ %opts ] )

Return a reference to a hash table where the keys are specified $datasets's $field value IDs and the values are references to arrays of IDs.

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dequeue_events

@events = $db->dequeue_events( $n )

Attempt to dequeue upto $n events. May return between 0 and $n events depending on parallel processes and how many events are remaining in the queue.

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ci_lookup

$value = $db->ci_lookup( $field, $value )

This is a hacky method to support case-insensitive lookup for usernames, emails, etc. It returns the actual case-sensitive version of $value if there is a case-insensitive match for the $field.

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Password Validation and Secret Fields

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valid_login

$db->valid_login( $username, $password )

Returns whether the clear-text $password matches the stored crypted password for the $username.

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secret_matches

$db->secret_matches( $dataobj, $fieldname, $token [, $callback ] )

Returns whether the clear-text $token matches the stored crypted field with $fieldname for the $dataobj according to the $callback function.

If not set, $callback defaults to EPrints::Utils#crypt_equals.

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is_secret_set

$boolean = $db->is_secret_set( $dataobj, $fieldname )

Returns a boolean for whether the secret $fieldname for $dataobj has a value set.

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Database Schema Manipulation

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has_sequence

$boolean = $db->has_sequence( $name )

Returns true if a sequence of the given $name exists in the database. Otherwise, returns false.

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create_sequence

$success = $db->create_sequence( $name )

Creates a new sequence object with $name and initialises to zero.

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drop_sequence

$success = $db->drop_sequence( $name )

Deletes a sequence object with $name.

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has_column

$boolean = $db->has_column( $table, $column )

Return true if the named $table has the named $column in the database.

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drop_column

$success = $db->drop_column( $table, $column )

Drops the named $column from the named $table.

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get_primary_key

@columns = $db->get_primary_key( $tablename )

Returns a list of column names that comprise the primary key for the $tablename.

Returns an empty list if no primary key exists.

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index_name

$name = $db->index_name( $table, @cols )

Returns the name of the first index that starts with named columns @cols in the named $table.

Returns undef if no index exists.

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get_index_ids

$ids = $db->get_index_ids( $table, $condition )

Return a reference to an array of the distinct primary keys from the named SQL $table which match the specified $condition.

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create_index

$success = $db->create_index( $table, @columns )

Creates an index over @columns for named $table. Returns true on success, false otherwise.

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create_unique_index

$success = $db->create_unique_index( $tablename, @columns )

Creates a unique index over @columns for named $table. Returns true on success, false otherwise.

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create_foreign_key

$ok = $db->create_foreign_key( $main_table, $table, $key_field )

Create a foreign key relationship between named $main_table and named $table using $key_field.

This will cause records in $table to be deleted if the equivalent record is deleted from $main_table.

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get_tables

@tables = $db->get_tables( [ $dbname ] )

Returns a list of all the tables in the database.

$dbname specifies a particular database name of current connection has access to more than one database.

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has_table

$boolean = $db->has_table( $tablename )

Returns boolean dependent on whether a table of the $tablename exists in the database.

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create_table

$success = $db->create_table( $tablename, $setkey, @fields );

Creates a new table with $tablename based on @fields.

The first $setkey number of fields are used for its primary key.

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drop_table

$db->drop_table( @tables )

Delete the named @tables. Use with caution!

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rename_table

$db->rename_table( $table_from, $table_to )

Renames the table named $table_from to $table_to.

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swap_table

$db->swap_table( $table_a, $table_b )

Renames table named $table_a to $table_b and vice-versa.

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EPrints Schema Manipulation

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create_archive_tables

$success = $db->create_archive_tables()

Create all the SQL tables for all datasets.

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drop_archive_tables

$db->drop_archive_tables()

Destroy all tables used by EPrints in the database.

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create_version_table

$db->create_version_table

Make the version table (and set the only value to be the current version of EPrints).

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drop_version_table

$db->drop_version_table

Drop the version table.

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has_dataset

$db->has_dataset( $dataset )

Returns true if $dataset exists in the database and has all expected tables including ordervalues and index tables.

This does not check that all fields are configured - see </has_field>.

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has_dataset_index_tables

$db->has_dataset_index_tables( $dataset )

Returns true if index tables for $dataset exists of if this is not indexable.

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create_dataset_tables

$success = $db->create_dataset_tables( $dataset )

Creates all the SQL tables for the specified $dataset.

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drop_dataset_tables

$db->drop_dataset_tables( $dataset )

Drops all the SQL tables for the specified $dataset.

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create_dataset_index_tables

$success = $db->create_dataset_index_tables( $dataset )

Creates all the index tables for the specified $dataset.

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create_dataset_ordervalues_tables

$success = $db->create_dataset_ordervalues_tables( $dataset )

Creates all the ordervalues tables for the specified $dataset.

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has_field

$db->has_field( $dataset, $field )

Returns true if $field is in the database for $dataset.

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add_field

$db->add_field( $dataset, $field, [ $force ] )

Add $field to $dataset's tables.

If $force is true modify/replace an existing column. Use with care!

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remove_field

$db->remove_field( $dataset, $field )

Remove $field from $dataset's tables.

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rename_field

$ok = $db->rename_field( $dataset, $field, $old_name )

Rename the $field in the $dataset from its $old_name.

Returns true if the $field is successfully renamed.

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create_counters

$success = $db->create_counters

Create the counters used to store the highest current ID of eprints, users, etc.

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has_counter

$success = $db->has_counter( $counter )

Returns true if $counter exists.

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create_counter

$success = $db->create_counter( $name )

Create and initialise to zero a new counter with $name.

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remove_counters

$success = $db->remove_counters

Destroy all counters.

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drop_counter

$success = $db->drop_counter( $name )

Destroy the counter named $name.

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User Messages

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save_user_message

$message = $db->save_user_message( $userid, $m_type, $dom_m_data )

Save user message provided in XML DOM object $dom_m_data as a sanitized string in a EPrints:DataObj::Message using $m_type to define the message type and $userid for the ID of the user whose message it is.

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get_user_messages

@messages = $db->get_user_messages( $userid, %opts )

Get the messages for a user with ID $userid and clear messages if $opt{clear} is set.

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clear_user_messages

$db->clear_user_messages( $userid )

Clear all messages for user with ID $userid.

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SEE ALSO

To access database-stored objects use the methods provided by the following modules: EPrints::Repository, EPrints::DataSet.

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COPYRIGHT

© Copyright 2022 University of Southampton.

EPrints 3.4 is supplied by EPrints Services.

http://www.eprints.org/eprints-3.4/

LICENSE

This file is part of EPrints 3.4 http://www.eprints.org/.

EPrints 3.4 and this file are released under the terms of the GNU Lesser General Public License version 3 as published by the Free Software Foundation unless otherwise stated.

EPrints 3.4 is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with EPrints 3.4. If not, see http://www.gnu.org/licenses/.

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