Difference between revisions of "API:EPrints/Database"

Latest revision as of 21:20, 4 March 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

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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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COPYRIGHT

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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@@ Line 1: / Line 1: @@
 <!-- Pod2Wiki=_preamble_
-This page has been automatically generated from the EPrints 3.2 source. Any wiki changes made between the 'Pod2Wiki=*' and 'Edit below this comment' comments will be lost.
+This page has been automatically generated from the EPrints 3.4 source. Any wiki changes made between the 'Pod2Wiki=*' and 'Edit below this comment' comments will be lost.
-  -->{{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 -->
+  -->{{API}}{{Pod2Wiki}}{{API:Source|file=EPrints/Database.pm|package_name=EPrints::Database}}[[Category:API|DATABASE]]<div><!-- Edit below this comment -->
 <!-- Pod2Wiki=_private_ --><!-- Pod2Wiki=head_name -->
 ==NAME==
-'''EPrints::Database''' - a connection to the SQL database for an eprints session
+'''EPrints::Database''' - a connection to the SQL database for an eprints session.
-<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 -->
-<!-- Pod2Wiki= -->
-</div>
-<!-- Pod2Wiki=head_synopsis -->
-==SYNOPSIS==
-  $db = $repo-&gt;database
-  $sth = $db-&gt;prepare("SELECT 'hello, world!'");
-  $sth-&gt;execute;
-  print $sth-&gt;fetchrow_arrayref-&gt;[0], "\n";
 <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>
@@ Line 33: / Line 19: @@
 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.
+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.
+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.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 46: / Line 32: @@
 <!-- Pod2Wiki=head_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.
+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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@@ Line 57: / Line 43: @@
 <!-- Pod2Wiki=head_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:
+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!" );
+ my $Q_value = $db-&gt;quote_value( "Hello, World!" );
-  $db-&gt;do("SELECT $Q_value");
+ $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.
+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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@@ Line 71: / Line 57: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=head_methods -->
+<!-- Pod2Wiki=head_constants -->
-==METHODS==
+==CONSTANTS==
+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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 <span style='display:none'>User Comments</span>
@@ Line 80: / Line 68: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=head_database -->
+<!-- Pod2Wiki=item_sql_null -->
-===Database===
+===SQL_NULL===
+A column value is undefined.
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 <span style='display:none'>User Comments</span>
@@ Line 89: / Line 80: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_new -->
+<!-- Pod2Wiki=item_sql_not_null -->
-====new====
+===SQL_NOT_NULL===
- $db = EPrints::Database-&gt;new( $repo )
+A column value is defined.
-Create a connection to the database.
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@@ Line 102: / Line 92: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_create -->
+<!-- Pod2Wiki=head_instance_variables -->
-====create====
+==INSTANCE VARIABLES==
- $db = $db-&gt;create( $username, $password )
-Create and connect to a new database using super user account $username and $password.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
 <span style='display:none'>User Comments</span>
@@ Line 115: / Line 101: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_connect -->
+<!-- Pod2Wiki=item_$self->{session} -->
-====connect====
+===$self-&gt;{session}===
-  $ok = $db-&gt;connect
+The [[API:EPrints/Session|EPrints::Session]] which is associated with this database  connection.
-Connects to the database.
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@@ Line 128: / Line 113: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_disconnect -->
+<!-- Pod2Wiki=item_$self->{debug} -->
-====disconnect====
+===$self-&gt;{debug}===
- $db-&gt;disconnect
+If <tt>true</tt> then SQL is logged.
-Disconnects from the EPrints database.
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@@ Line 141: / Line 125: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_set_debug -->
+<!-- Pod2Wiki=item_$self->{dbh} -->
-====set_debug====
+===$self-&gt;{dbh}===
- $db-&gt;set_debug( $boolean )
+The handle on the actual database connection.
-Set the SQL debug mode to true or false.
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@@ Line 154: / Line 137: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_set_version -->
+<!-- Pod2Wiki=head_methods -->
-====set_version====
+==METHODS==
+<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 -->
- $db-&gt;set_version( $versionid );
-Set the version id table in the SQL database to the given value (used by the upgrade script).
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=head_database -->
+===Database===
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 <span style='display:none'>User Comments</span>
@@ Line 167: / Line 155: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_get_version -->
+<!-- Pod2Wiki=item_new -->
-====get_version====
+====new====
+ $db = EPrints::Database-&gt;new( $repo, [ %opts ] )
+Create a connection to the database.
- $version = $db-&gt;get_version
+Options:
-Returns the current database schema version.
+  db_connect - Boolean. Also connect to the database (default: true).
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@@ Line 180: / Line 171: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_is_latest_version -->
+<!-- Pod2Wiki=item_create -->
-====is_latest_version====
+====create====
-  $boolean = $db-&gt;is_latest_version
+  $db = $db-&gt;create( $username, $password )
-Return true if the database schema is in the correct configuration for this version of eprints. Otherwise false.
+Create and connect to a new database using user account <tt>$username</tt>  and <tt>$password</tt>.
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@@ Line 193: / Line 184: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_get_server_version -->
+<!-- Pod2Wiki=item_build_connection_string -->
-====get_server_version====
+====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}}.
-  $version = $db-&gt;get_server_version
+Parameters:
-Return the database server version.
+ 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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@@ Line 206: / Line 204: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_get_default_charset -->
+<!-- Pod2Wiki=item_connect -->
-====get_default_charset====
+====connect====
-  $charset = $db-&gt;get_default_charset( LANGUAGE )
+  $db-&gt;connect()
-Return the character set to use for LANGUAGE.
+Connects to the database.
-Returns undef if character sets are unsupported.
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@@ Line 221: / Line 217: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_get_default_collation -->
+<!-- Pod2Wiki=item_disconnect -->
-====get_default_collation====
+====disconnect====
-  $collation = $db-&gt;get_default_collation( LANGUAGE )
+  $db-&gt;disconnect()
-Return the collation to use for LANGUAGE.
+Disconnects from the EPrints database. Should always be done before  any script exits.
-Returns undef if collation is unsupported.
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@@ Line 236: / Line 230: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_get_driver_name -->
+<!-- Pod2Wiki=item_set_debug -->
-====get_driver_name====
+====set_debug====
-  $driver = $db-&gt;get_driver_name
+  $db-&gt;set_debug( $boolean )
-Return the database driver name.
+Set the SQL debug mode to <tt>true</tt> or <tt>false</tt>.
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@@ Line 249: / Line 243: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_error -->
+<!-- Pod2Wiki=item_set_version -->
-====error====
+====set_version====
-  $errstr = $db-&gt;error
+  $db-&gt;set_version( $versionid );
-Return a string describing the last SQL error.
+Set the version id table in the SQL database to the given <tt>versionid</tt> (used by the upgrade script).
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@@ Line 262: / Line 256: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_retry_error -->
+<!-- Pod2Wiki=item_get_version -->
-====retry_error====
+====get_version====
-  $bool = $db-&gt;retry_error
+  $version = $db-&gt;get_version
-Returns true if the current error is a retry error.
+Returns the current database schema version.
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@@ Line 275: / Line 269: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_duplicate_error -->
+<!-- Pod2Wiki=item_is_latest_version -->
-====duplicate_error====
+====is_latest_version====
-  $bool = $db-&gt;duplicate_error
+  $boolean = $db-&gt;is_latest_version
-Returns true if the current error is a PRIMARY KEY or UNIQUE error.
+Return <tt>true</tt> if the SQL tables are in the correct configuration for this edition of eprints. Otherwise, <tt>false</tt>.
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@@ Line 288: / Line 282: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_begin -->
+<!-- Pod2Wiki=item_get_server_version -->
-====begin====
+====get_server_version====
-  $db-&gt;begin
+  $version = $db-&gt;get_server_version
-Begin a transaction.
+Return the database server version.
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@@ Line 301: / Line 295: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_commit -->
+<!-- Pod2Wiki=item_get_default_charset -->
-====commit====
+====get_default_charset====
+ $charset = $db-&gt;get_default_charset
+Return the character set to use.
- $db-&gt;commit
+Returns <tt>undef</tt> if character sets are unsupported.
-Commit the previously begun transaction.
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@@ Line 314: / Line 310: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_rollback -->
+<!-- Pod2Wiki=item_get_default_collation -->
-====rollback====
+====get_default_collation====
+ $collation = $db-&gt;get_default_collation( $lang )
+Return the collation to use for language <tt>$lang</tt>.
- $db-&gt;rollback
+Returns <tt>undef</tt> if collation is unsupported.
-Roll-back the current transaction.
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@@ Line 327: / Line 325: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_type_info -->
+<!-- Pod2Wiki=item_get_driver_name -->
-====type_info====
+====get_driver_name====
-  $type_info = $db-&gt;type_info( DATA_TYPE )
+  $driver = $db-&gt;get_driver_name
-See {{API:PodLink|file=DBI|package_name=DBI|section=type_info|text=DBI/type_info}}.
+Return the database driver name.
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@@ Line 340: / Line 338: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_get_column_type -->
+<!-- Pod2Wiki=item_error -->
-====get_column_type====
+====error====
-  $real_type = $db-&gt;get_column_type( NAME, TYPE, NOT_NULL, [ LENGTH/PRECISION ], [ SCALE ], %opts )
+  $errstr = $db-&gt;error()
-Returns a SQL column definition for NAME of type TYPE, usually something like:
+Return a string describing the last SQL error.
-  $name $type($length,$scale) [ NOT NULL ]
+<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>
-If NOT_NULL is true column will be set "not null".
+<!-- Edit below this comment -->
-LENGTH/PRECISION and SCALE control the maximum lengths of character or decimal types (see below).
-Other options available to refine the column definition:
+<!-- Pod2Wiki= -->
+</div>
-  langid - character set/collation to use
+<!-- Pod2Wiki=item_retry_error -->
-  sorted - whether this column will be used to order by
+====retry_error====
-'''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.
-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.
+ $boolean = $db-&gt;retry_error()
+Returns a boolean for whether the database error is a retry error.
-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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@@ Line 384: / Line 364: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=head_schema_manipulation -->
+<!-- Pod2Wiki=item_duplicate_error -->
-===Schema Manipulation===
+====duplicate_error====
+ $boolean = $db-&gt;duplicate_error()
+Returns a boolean for whether the database error is a duplicate error.
 <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>
@@ Line 393: / Line 377: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_create_archive_tables -->
+<!-- Pod2Wiki=item_begin -->
-====create_archive_tables====
+====begin====
-  $success = $db-&gt;create_archive_tables
+  $db-&gt;begin()
-Create all the SQL tables for each dataset.
+Begin a transaction.
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@@ Line 406: / Line 390: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_drop_archive_tables -->
+<!-- Pod2Wiki=item_commit -->
-====drop_archive_tables====
+====commit====
-  $db-&gt;drop_archive_tables()
+  $db-&gt;commit()
-Destroy all tables used by eprints in the database.
+Commit the previously begun transaction.
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@@ Line 419: / Line 403: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_create_version_table -->
+<!-- Pod2Wiki=item_rollback -->
-====create_version_table====
+====rollback====
-  $db-&gt;create_version_table
+  $db-&gt;rollback()
-Make the version table (and set the only value to be the current version of eprints).
+Rollback the partially completed transaction.
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@@ Line 432: / Line 416: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_drop_version_table -->
+<!-- Pod2Wiki=item_type_info -->
-====drop_version_table====
+====type_info====
-  $db-&gt;drop_version_table
+  $type_info = $db-&gt;type_info( $data_type )
-Drop the version table.
+See {{API:PodLink|file=DBI|package_name=DBI|section=type_info|text=DBI/type_info}}.
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@@ Line 445: / Line 429: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_create_dataset_tables -->
+<!-- Pod2Wiki=item_get_column_type -->
-====create_dataset_tables====
+====get_column_type====
-  $success = $db-&gt;create_dataset_tables( $dataset )
+  $real_type = $db-&gt;get_column_type( $name, $data_type, $not_null, [ $length, $scale, %opts ] )
-Create all the SQL tables for a single dataset.
+Returns a SQL column definition for <tt>$name</tt> of type <tt>$type</tt>, usually something like:
+  $name $type($length,$scale) [ NOT NULL ]
+If <tt>$not_null</tt> is <tt>true</tt> column will be set to <tt>NOT NULL</tt>.
+<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:
+  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 <tt>sorted</tt> is true, the database may use a substitute column type.
+<tt>$data_type</tt> is the SQL type. The types are constants defined by this module, to import them use:
+  use EPrints::Database qw( :sql_types );
+Supported types (n = requires <tt>$length</tt> argument):
+Character data: <tt>SQL_VARCHAR(n)</tt>, <tt>SQL_LONGVARCHAR</tt>, <tt>SQL_CLOB</tt>.
+Binary data: <tt>SQL_VARBINARY(n)</tt>, <tt>SQL_LONGVARBINARY</tt>.
-<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
+Integer data: <tt>SQL_TINYINT</tt>, <tt>SQL_SMALLINT</tt>, <tt>SQL_INTEGER</tt>, <tt>SQL_BIGINT</tt>.
-<span style='display:none'>User Comments</span>
-<!-- Edit below this comment -->
+Floating-point data: <tt>SQL_REAL</tt>, <tt>SQL_DOUBLE</tt>.
-<!-- Pod2Wiki= -->
+Time data: <tt>SQL_DATE</tt>, <tt>SQL_TIME</tt>.
-</div>
-<!-- Pod2Wiki=item_drop_dataset_tables -->
-====drop_dataset_tables====
- $db-&gt;drop_dataset_tables( $dataset )
+The actual column types used will be database-specific.
-Drop all the SQL tables for a single dataset.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 471: / Line 473: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_create_dataset_index_tables -->
+<!-- Pod2Wiki=head_basic_sql_operations -->
-====create_dataset_index_tables====
+===Basic SQL Operations===
- $success = $db-&gt;create_dataset_index_tables( $dataset )
-Create all the index tables for a single dataset.
 <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>
@@ Line 484: / Line 482: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_create_dataset_ordervalues_tables -->
+<!-- Pod2Wiki=item_do -->
-====create_dataset_ordervalues_tables====
+====do====
-  $success = $db-&gt;create_dataset_ordervalues_tables( $dataset )
+  $success = $db-&gt;do( $sql )
-Create all the ordervalues tables for a single dataset.
+Execute the given <tt>$sql</tt>.
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@@ Line 497: / Line 495: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_has_dataset -->
+<!-- Pod2Wiki=item_prepare -->
-====has_dataset====
+====prepare====
-  $db-&gt;has_dataset( $dataset )
+  $sth = $db-&gt;prepare( $sql )
-Returns true if $dataset exists in the database or has no database tables.
+Prepare the given <tt>$sql</tt> and return a handle on it.
-This does not check that all fields are configured - see has_field().
+Use the <tt>execute</tt> method on the returned {{API:PodLink|file=DBI|package_name=DBI|section=|text=DBI}} handle to execute the SQL:
+  my $sth = $db-&gt;prepare_select( "SELECT 'Hello, World'" );
+  $sth-&gt;execute;
 <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>
@@ Line 512: / Line 513: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_has_field -->
+<!-- Pod2Wiki=item_prepare_select -->
-====has_field====
+====prepare_select====
-  $db-&gt;has_field( $dataset, $field )
+  $sth = $db-&gt;prepare_select( $sql, [ %options ] )
-Returns true if $field is in the database for $dataset.
+Prepare a <tt>SELECT</tt> statement <tt>$sql</tt> and return a handle to it. After  preparing a statement use <tt>execute()</tt> to execute it.
-<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
+Returns a {{API:PodLink|file=DBI|package_name=DBI|section=|text=DBI}} statement handle.
-<span style='display:none'>User Comments</span>
-<!-- Edit below this comment -->
+The <tt>LIMIT</tt> SQL keyword is not universally supported, to specify this  use the <tt>limit</tt> option.
-<!-- Pod2Wiki= -->
+Options:
-</div>
-<!-- Pod2Wiki=item_add_field -->
-====add_field====
- $db-&gt;add_field( $dataset, $field [, $force ] )
-Add $field to $dataset's tables.
-If $force is true will modify/replace an existing column (use with care!).
+  limit - limit the number of rows returned
+  offset - return '''limit''' number of rows after offset
 <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>
@@ Line 540: / Line 535: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_remove_field -->
+<!-- Pod2Wiki=item_execute -->
-====remove_field====
+====execute====
-  $db-&gt;remove_field( $dataset, $field )
+  $success = $db-&gt;execute( $sth, $sql )
-Remove $field from $dataset's tables.
+Execute the SQL prepared earlier in the <tt>$sth</tt>. <tt>$sql</tt> is only  required for debugging purposes.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 553: / Line 548: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_rename_field -->
+<!-- Pod2Wiki=item_update -->
-====rename_field====
+====update====
-  $ok = $db-&gt;rename_field( $dataset, $field, $old_name )
+  $success = $db-&gt;update( $dataset, $data, $changed )
-Rename a $field in the database from it's old name $old_name.
+Updates a <tt>EPrints::DataObj</tt> from <tt>$dataset</tt> with the given <tt>$data</tt>.  The primary key field (e.g. <tt>eprintid</tt>) value must be included.
-Returns true if the field was successfully renamed.
+Updates the <tt>ordervalues</tt> if the <tt>$dataset</tt> is  {{API:PodLink|file=EPrints/DataSet#ordered|package_name=EPrints::DataSet#ordered|section=|text=ordered}}.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 568: / Line 563: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_create_table -->
+<!-- Pod2Wiki=item__update -->
-====create_table====
+====_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.
-  $success = $db-&gt;create_table( $tablename, $setkey, @fields );
+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.
-Creates a new table $tablename based on @fields.
-The first $setkey number of fields are used for a primary key.
+This is an internal method.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 583: / Line 580: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_create_foreign_key -->
+<!-- Pod2Wiki=item_insert -->
-====create_foreign_key====
+====insert====
-  $ok = $db-&gt;create_foreign_key( $main_table, $aux_table, $key_field )
+  $success = $db-&gt;insert( $table, $columns, @values )
-Create a foreign key relationship between $main_table and $aux_table using the $key_field.
+Inserts <tt>@values</tt> into the table <tt>$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.
-This will cause records in $aux_table to be deleted if the equivalent record is deleted from $main_table.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 598: / Line 593: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_create_counters -->
+<!-- Pod2Wiki=item_insert_quoted -->
-====create_counters====
+====insert_quoted====
-  $success = $db-&gt;create_counters
+  $success = $db-&gt;insert_quoted( $table, $columns, @qvalues )
-Create the counters used to store the highest current id of eprints, users etc.
+Inserts values into the table <tt>$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!
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 611: / Line 606: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_has_counter -->
+<!-- Pod2Wiki=item_delete_from -->
-====has_counter====
+====delete_from====
+ $success = $db-&gt;delete_from( $table, $columns, @values )
+Perform a SQL <tt>DELETE FROM</tt> <tt>$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>.
- $success = $db-&gt;has_counter( $counter )
+If you want to clear a table completely use <tt>clear_table()</tt>.
-Returns true if $counter exists.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 624: / Line 621: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_create_counter -->
+<!-- Pod2Wiki=item_count_table -->
-====create_counter====
+====count_table====
-  $success = $db-&gt;create_counter( $name )
+  $n = $db-&gt;count_table( $tablename )
-Create and initialise to zero a new counter called $name.
+Return the number of rows in the specified SQL table with  <tt>$tablename</tt>.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 637: / Line 634: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_remove_counters -->
+<!-- Pod2Wiki=item_clear_table -->
-====remove_counters====
+====clear_table====
-  $success = $db-&gt;remove_counters
+  $db-&gt;clear_table( $tablename )
-Destroy all counters.
+Clears all records from the given table with <tt>$tablename</tt>. Use with  caution!
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@@ Line 650: / Line 647: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_drop_counter -->
+<!-- Pod2Wiki=head_quoting -->
-====drop_counter====
+===Quoting===
- $success = $db-&gt;drop_counter( $name )
-Destroy the counter named $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>
@@ Line 663: / Line 656: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_counter_current -->
+<!-- Pod2Wiki=item_prep_int -->
-====counter_current====
+====prep_int====
-  $n = $db-&gt;counter_current( $counter )
+  $mungedvalue = EPrints::Database::prep_int( $value )
-Return the value of the previous counter_next on $counter.
+Escape numerical <tt>$value</tt> for an SQL statement. <tt>undef</tt> becomes  <tt>NULL</tt>. 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%; '>
@@ Line 676: / Line 669: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_counter_next -->
+<!-- Pod2Wiki=item_prep_value -->
-====counter_next====
+====prep_value====
-  $n = $db-&gt;counter_next( $counter )
+  $mungedvalue = EPrints::Database::prep_value( $value )
-Return the next unused value for the named counter. Returns undef if  the counter doesn't exist.
+Escape <tt>$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>.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 689: / Line 682: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_counter_minimum -->
+<!-- Pod2Wiki=item_prep_like_value -->
-====counter_minimum====
+====prep_like_value====
-  $db-&gt;counter_minimum( $counter, $value )
+  $mungedvalue = EPrints::Database::prep_like_value( $value )
-Ensure that the counter is set no lower than $value. This is used when importing eprints which may not be in scrict sequence.
+Escape <tt>$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>.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 702: / Line 695: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_counter_reset -->
+<!-- Pod2Wiki=item_quote_value -->
-====counter_reset====
+====quote_value====
-  $db-&gt;counter_reset( $counter )
+  $str = $db-&gt;quote_value( $value )
-Reset the counter. Use with caution.
+Return a quoted version of <tt>$value</tt>. To quote a <tt>LIKE</tt> value  you should use:
+ $db-&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%; '>
 <span style='display:none'>User Comments</span>
@@ Line 715: / Line 710: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_next_doc_pos -->
+<!-- Pod2Wiki=item_quote_int -->
-====next_doc_pos====
+====quote_int====
-  $n = $db-&gt;next_doc_pos( $eprintid )
+  $str = $db-&gt;quote_int( $value )
-Return the next unused document pos for the given eprintid.
+Return a quoted integer for <tt>$value</tt>.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 728: / Line 723: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=head_sql_utility_methods -->
+<!-- Pod2Wiki=item_quote_binary -->
-===SQL utility methods===
+====quote_binary====
+ $str = $db-&gt;quote_binary( $bytes )
+Some databases (Oracle/PostgreSQL) require transforms of binary data  to work correctly.
+This method should be called on data <tt>$bytes</tt> containing null bytes  or back-slashes before being passed on [[API:EPrints/Database#quote_value|quote_value]].
 <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>
@@ Line 737: / Line 738: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_do -->
+<!-- Pod2Wiki=item_quote_ordervalue -->
-====do====
+====quote_ordervalue====
-  $success = $db-&gt;do( $sql )
+  $str = $db-&gt;quote_ordervalue( $field, $value )
-Execute the given SQL.
+Some databases (Oracle) can't order by <tt>CLOB</tt>s so need special  treatment when creating the ordervalues tables. This method allows any  fixing-up required for string data <tt>$value</tt> for <tt>$field</tt> before it's  inserted.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 750: / Line 751: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_prepare -->
+<!-- Pod2Wiki=item_quote_identifier -->
-====prepare====
+====quote_identifier====
-  $sth = $db-&gt;prepare( $sql )
+  $str = $db-&gt;quote_identifier( @parts )
-Prepare the SQL statement $sql for execution.
+Quote a database identifier (e.g. table names). Multiple <tt>@parts</tt>  will be joined by dots (<tt>.</tt>).
-Use the <tt>execute</tt> method on the returned {{API:PodLink|file=DBI|package_name=DBI|section=|text=DBI}} handle to execute the SQL:
-  my $sth = $db-&gt;prepare_select( "SELECT 'Hello, World'" );
-  $sth-&gt;execute;
 <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>
@@ Line 768: / Line 764: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_prepare_select -->
+<!-- Pod2Wiki=item_prepare_regexp -->
-====prepare_select====
+====prepare_regexp====
-  $sth = $db-&gt;prepare_select( $sql [, %options ] )
+  $sql = $db-&gt;prepare_regexp( $col, $value )
-Prepare a SELECT statement $sql for execution.
+The syntax used for regular expressions varies across databases. This  method takes two quoted string and returns a SQL expression that will  apply the quoted regexp <tt>$value</tt> to the quoted column <tt>$col</tt>.
-Returns a {{API:PodLink|file=DBI|package_name=DBI|section=|text=DBI}} statement handle.
-The LIMIT SQL keyword is not universally supported, to specify a LIMIT you must use the '''limit''' option.
-Options:
-  limit - limit the number of rows returned
-  offset - return '''limit''' number of rows after offset
 <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>
@@ Line 790: / Line 777: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_has_sequence -->
+<!-- Pod2Wiki=item_sql_as -->
-====has_sequence====
+====sql_as====
-  $boolean = $db-&gt;has_sequence( $name )
+  $sql = $db-&gt;sql_AS()
-Return true if a sequence of the given name exists in the database.
+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%; '>
@@ Line 803: / Line 790: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_create_sequence -->
+<!-- Pod2Wiki=item_sql_like -->
-====create_sequence====
+====sql_like====
-  $success = $db-&gt;create_sequence( $seq_name )
+  $sql = $db-&gt;sql_LIKE()
-Creates a new sequence object initialised to zero.
+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.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 816: / Line 803: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_drop_sequence -->
+<!-- Pod2Wiki=head_counters -->
-====drop_sequence====
+===Counters===
- $success = $db-&gt;drop_sequence( $seq_name )
-Deletes a sequence object.
 <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>
@@ Line 829: / Line 812: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_drop_column -->
+<!-- Pod2Wiki=item_counter_current -->
-====drop_column====
+====counter_current====
-  $success = $db-&gt;drop_column( $table, $column )
+  $n = $db-&gt;counter_current( $counter )
-Drops a column from a table.
+Return the value of the previous counter_next on <tt>$counter</tt>.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 842: / Line 825: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_get_primary_key -->
+<!-- Pod2Wiki=item_counter_next -->
-====get_primary_key====
+====counter_next====
-  @columns = $db-&gt;get_primary_key( $tablename )
+  $n = $db-&gt;counter_next( $counter )
-Returns the list of column names that comprise the primary key for $tablename.
+Return the next unused value for the named <tt>$counter</tt>. Returns  <tt>undef</tt> if the <tt>$counter</tt> doesn't exist.
-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%; '>
@@ Line 857: / Line 838: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_create_primary_key -->
+<!-- Pod2Wiki=item_counter_minimum -->
-====create_primary_key====
+====counter_minimum====
-  $db-&gt;create_primary_key( $tablename, @cols )
+  $db-&gt;counter_minimum( $counter, $value )
-Create a PRIMARY KEY on $tablename over @cols.
+Ensure that the <tt>$counter</tt> is set no lower than <tt>$value</tt>. This is  used when importing eprints which may not be in scrict sequence.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 870: / Line 851: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_create_index -->
+<!-- Pod2Wiki=item_counter_reset -->
-====create_index====
+====counter_reset====
-  $success = $db-&gt;create_index( $tablename, @columns )
+  $db-&gt;counter_reset( $counter )
-Creates an index over @columns for $tablename. Returns true on success.
+Reset the <tt>$counter</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%; '>
@@ Line 883: / Line 864: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_create_unique_index -->
+<!-- Pod2Wiki=item_next_doc_pos -->
-====create_unique_index====
+====next_doc_pos====
-  $success = $db-&gt;create_unique_index( $tablename, @columns )
+  $n = $db-&gt;next_doc_pos( $eprintid )
-Creates a unique index over @columns for $tablename. Returns true on success.
+Return the next unused document position for the given <tt>$eprintid</tt>.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 896: / Line 877: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_index_name -->
+<!-- Pod2Wiki=head_dataset_data -->
-====index_name====
+===Dataset Data===
- $name = $db-&gt;index_name( $table, @columns )
-Returns the name of the first index that starts with @columns on the $table table.
-Returns undef if no index 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>
@@ Line 911: / Line 886: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item__update -->
+<!-- Pod2Wiki=item_exists -->
-====_update====
+====exists====
-  $rows = $db-&gt;_update( $tablename, $keycols, $keyvals, $columns, @values )
+  $boolean = $db-&gt;exists( $dataset, $id )
-UPDATES $tablename where $keycols equals $keyvals and returns the number of rows affected.
+Return <tt>true</tt> if there exists an [[API:EPrints/DataObj|EPrints::DataObj]] from the  <tt>$dataset</tt> with its primary key set to <tt>$id</tt>. Otherwise, return  <tt>false</tt>.
-Note! If no rows are affected the result is still 'true', see DBI's execute() method.
-This method is internal.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 928: / Line 899: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_insert -->
+<!-- Pod2Wiki=item_add_record -->
-====insert====
+====add_record====
-  $success = $db-&gt;insert( $table, $columns, @values )
+  $success = $db-&gt;add_record( $dataset, $data )
-Inserts values into the table $table. If $columns is defined it will be used as a list of columns to insert into. @values is a list of arrays containing values to insert.
+Add the given <tt>$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>.
-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%; '>
@@ Line 943: / Line 912: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_insert_quoted -->
+<!-- Pod2Wiki=item_remove -->
-====insert_quoted====
+====remove====
-  $success = $db-&gt;insert_quoted( $table, $columns, @qvalues )
+  $success = $db-&gt;remove( $dataset, $id )
-Inserts values into the table $table. If $columns is defined it will be used as a list of columns to insert into. @qvalues is a list of arrays containing values to insert.
+Attempts to remove the [[API:EPrints/DataObj|EPrints::DataObj]] with the primary key <tt>$id</tt>  from the specified <tt>$dataset</tt>.
-Values will NOT be quoted before insertion - care must be exercised!
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 958: / Line 925: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_delete_from -->
+<!-- Pod2Wiki=head_searching_caching_and_object_retrieval -->
-====delete_from====
+===Searching, caching and object retrieval===
- $success = $db-&gt;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().
 <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>
@@ Line 973: / Line 934: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_count_table -->
+<!-- Pod2Wiki=item_cache_exp -->
-====count_table====
+====cache_exp====
-  $n = $db-&gt;count_table( $tablename )
+  $searchexp = $db-&gt;cache_exp( $cacheid )
-Return the number of rows in the specified SQL table.
+Return the serialised search of a the cached search with <tt>$cacheid</tt>. Return <tt>undef</tt> if the <tt>$cacheid</tt> is invalid or expired.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 986: / Line 947: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_has_table -->
+<!-- Pod2Wiki=item_cache -->
-====has_table====
+====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>.
+If <tt>$order</tt> is set then the cache is ordered by the specified fields.  For example <tt>-year/title</tt> orders by year (descending). Records with  the same year are ordered by title.
+If <tt>$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>.
- $boolean = $db-&gt;has_table( $tablename )
+If <tt>$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 table 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%; '>
@@ Line 999: / Line 966: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_has_column -->
+<!-- Pod2Wiki=item_cache_table -->
-====has_column====
+====cache_table====
-  $boolean = $db-&gt;has_column( $tablename, $columnname )
+  $tablename = $db-&gt;cache_table( $id )
-Return true if the a table of the given name has a column named $columnname in the database.
+Return the name of the SQL table used to store the cache with <tt>$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%; '>
@@ Line 1,012: / Line 979: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_drop_table -->
+<!-- Pod2Wiki=item_cache_userid -->
-====drop_table====
+====cache_userid====
-  $db-&gt;drop_table( $tablename [, $tablename2 ] )
+  $userid = $db-&gt;cache_userid( $id )
-Delete the named table(s). Use with caution!
+Returns the <tt>userid</tt> associated with the cache with <tt>$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%; '>
@@ Line 1,025: / Line 992: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_clear_table -->
+<!-- Pod2Wiki=item_get_cachemap -->
-====clear_table====
+====get_cachemap====
-  $db-&gt;clear_table( $tablename )
+  $cachemap = $db-&gt;get_cachemap( $id )
-Clears all records from the given table, use with caution!
+Return the cachemap with $&lt;id&gt;.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,038: / Line 1,005: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_rename_table -->
+<!-- Pod2Wiki=item_search -->
-====rename_table====
+====search====
+ $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.
- $db-&gt;rename_table( $tablename, $newtablename )
+If no <tt>$main_table_alias</tt> is specified then <tt>M</tt> is assumed.
-Renames the table from the old name to the new one.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,051: / Line 1,020: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_swap_table -->
+<!-- Pod2Wiki=item_drop_cache -->
-====swap_table====
+====drop_cache====
-  $db-&gt;swap_table( $table_a, $table_b )
+  $db-&gt;drop_cache( $id )
-Swap table a and table b.
+Remove the cached search with the given <tt>$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%; '>
@@ Line 1,064: / Line 1,033: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_get_tables -->
+<!-- Pod2Wiki=item_from_cache -->
-====get_tables====
+====from_cache====
-  @tables = $db-&gt;get_tables
+  $items = $db-&gt;from_cache( $dataset, $cacheid, [ $offset, $count, $justids ] )
-Return a list of all the tables in the database.
+Return a reference to an array containing all the items from the given  <tt>$dataset</tt> that have IDs in the cache specified by <tt>$cacheid</tt>. The  cache may be specified either by ID or serialised search expression.
-<div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
+<tt>$offset</tt> is an offset from the start of the cache and <tt>$count</tt> is  the number of records to return.
-<span style='display:none'>User Comments</span>
-<!-- Edit below this comment -->
+If <tt>$justids</tt> is <tt>true</tt> then it returns just a reference to an array  of the record IDs and not the objects themselves.
-<!-- Pod2Wiki= -->
-</div>
-<!-- Pod2Wiki=head_quoting_values -->
-===Quoting 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>
@@ Line 1,086: / Line 1,050: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_prep_int -->
+<!-- Pod2Wiki=item_drop_orphan_cache_tables -->
-====prep_int====
+====drop_orphan_cache_tables====
-  $mungedvalue = EPrints::Database::prep_int( $value )
+  $c = $db-&gt;drop_orphan_cache_tables
-Escape a numerical value for SQL. undef becomes NULL. Anything else becomes a number (zero if needed).
+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%; '>
@@ Line 1,099: / Line 1,063: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_prep_value -->
+<!-- Pod2Wiki=item_get_single -->
-====prep_value====
+====get_single====
-  $mungedvalue = EPrints::Database::prep_value( $value )
+  $obj = $db-&gt;get_single( $dataset, $id )
-Escape a value for SQL. Modify value such that " becomes \" and \  becomes \\ and ' becomes \'
+Return a single &lt;EPrints::DataObj&gt; from the given <tt>$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%; '>
@@ Line 1,112: / Line 1,076: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_prep_like_value -->
+<!-- Pod2Wiki=item_get_all -->
-====prep_like_value====
+====get_all====
-  $mungedvalue = EPrints::Database::prep_like_value( $value )
+  $items = $db-&gt;get_all( $dataset )
-Escape an value for an SQL like field. In addition to ' " and \ also  escapes % and _
+Returns a reference to an array with all the &lt;EPrints::DataObj&gt;s from  the given <tt>$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%; '>
@@ Line 1,125: / Line 1,089: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_quote_value -->
+<!-- Pod2Wiki=item_get_cache_ids -->
-====quote_value====
+====get_cache_ids====
-  $str = $db-&gt;quote_value( $value )
+  @ids = $db-&gt;get_cache_ids( $dataset, $cachemap, $offset, $count )
-Return a quoted value. To quote a 'like' value you should do:
+Returns a list of <tt>$count</tt> IDs from <tt>$cache_id</tt> starting at  <tt>$offset</tt> and in the order in the <tt>$cachemap</tt>.
- 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%; '>
 <span style='display:none'>User Comments</span>
@@ Line 1,140: / Line 1,102: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_quote_int -->
+<!-- Pod2Wiki=item_get_dataobjs -->
-====quote_int====
+====get_dataobjs====
-  $str = $db-&gt;quote_int( $value )
+  @dataobjs = $db-&gt;get_dataobjs( $dataset, [ $id, $id, ... ] )
-Return a quoted integer value
+Retrieves the records in <tt>$dataset</tt> with the given <tt>$id</tt>(s). If an  <tt>$id</tt> doesn't exist in the database it will be ignored.
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@@ Line 1,153: / Line 1,115: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_quote_binary -->
+<!-- Pod2Wiki=item_get_values -->
-====quote_binary====
+====get_values====
- $str = $db-&gt;quote_binary( $bytes )
-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]].
+ $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%; '>
@@ Line 1,168: / Line 1,128: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_quote_ordervalue -->
+<!-- Pod2Wiki=item_sort_values -->
-====quote_ordervalue====
+====sort_values====
-  $str = $db-&gt;quote_ordervalue( $field, $value )
+  $values = $db-&gt;sort_values( $field, $values, [ $langid ] )
-Some databases (Oracle) can't order by CLOBS so need special treatment when creating the ordervalues tables. This method allows any fixing-up required for string data before it's inserted.
+Sorts and returns the list of <tt>$values</tt> using the database.
+<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%; '>
@@ Line 1,181: / Line 1,143: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_quote_identifier -->
+<!-- Pod2Wiki=item_get_ids_by_field_values -->
-====quote_identifier====
+====get_ids_by_field_values====
-  $str = $db-&gt;quote_identifier( @parts )
+  $ids = $db-&gt;get_ids_by_field_values( $field, $dataset, [ %opts ] )
-Quote a database identifier (e.g. table names). Multiple @parts will be joined by dot.
+Return a reference to a hash table where the keys are specified  <tt>$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%; '>
@@ Line 1,194: / Line 1,156: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_prepare_regexp -->
+<!-- Pod2Wiki=item_dequeue_events -->
-====prepare_regexp====
+====dequeue_events====
-  $sql = $db-&gt;prepare_regexp( $quoted_column, $quoted_value )
+  @events = $db-&gt;dequeue_events( $n )
-The syntax used for regular expressions varies across databases. This method takes two '''quoted''' values and returns a SQL expression that will apply the regexp ($quoted_value) to the column ($quoted_column).
+Attempt to dequeue upto <tt>$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%; '>
@@ Line 1,207: / Line 1,169: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_sql_as -->
+<!-- Pod2Wiki=item_ci_lookup -->
-====sql_as====
+====ci_lookup====
-  $sql = $db-&gt;sql_AS()
+  $value = $db-&gt;ci_lookup( $field, $value )
-Returns the syntactic glue to use when aliasing. SQL 92 DBs will happilly use " AS " but some DBs (Oracle!) won't accept it.
+This is a hacky method to support case-insensitive lookup for usernames, emails, etc.  It returns the actual case-sensitive version of <tt>$value</tt> if there is a case-insensitive match for the <tt>$field</tt>.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,220: / Line 1,182: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_sql_like -->
+<!-- Pod2Wiki=head_password_validation_and_secret_fields -->
-====sql_like====
+===Password Validation and Secret Fields===
- $sql = $db-&gt;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.
 <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>
@@ Line 1,233: / Line 1,191: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=head_dataset_data -->
+<!-- Pod2Wiki=item_valid_login -->
-===Dataset Data===
+====valid_login====
+ $db-&gt;valid_login( $username, $password )
+Returns whether the clear-text <tt>$password</tt> matches the stored crypted  password for the <tt>$username</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>
@@ Line 1,242: / Line 1,204: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_insert_data -->
+<!-- Pod2Wiki=item_secret_matches -->
-====insert_data====
+====secret_matches====
-  $success = $db-&gt;insert_data( $dataset, $data )
+  $db-&gt;secret_matches( $dataobj, $fieldname, $token [, $callback ] )
-Add the given data as a new record in the given dataset. $data is a reference to a hash containing values structured for a record in the that dataset.
+Returns whether the clear-text <tt>$token</tt> matches the stored crypted  field with <tt>$fieldname</tt> for the <tt>$dataobj</tt> according to the  <tt>$callback</tt> function.
-Returns undef if a record already exists with the key field value in $data.
+If not set, <tt>$callback</tt> defaults to [[API:EPrints/Utils#crypt_equals|EPrints::Utils#crypt_equals]].
-Inserts ordervalues if the dataset is {{API:PodLink|file=EPrints/DataSet|package_name=EPrints::DataSet|section=ordered|text=ordered}}.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,259: / Line 1,219: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_update_data -->
+<!-- Pod2Wiki=item_is_secret_set -->
-====update_data====
+====is_secret_set====
-  $success = $db-&gt;update_data( $dataset, $data, $changed )
+  $boolean = $db-&gt;is_secret_set( $dataobj, $fieldname )
-Updates a record in the given {{API:PodLink|file=EPrints/DataSet|package_name=EPrints::DataSet|section=|text=$dataset}}. $data is a copy of the entire record's data and $changed the values that have changed.
+Returns a boolean for whether the secret <tt>$fieldname</tt> for <tt>$dataobj</tt>  has a value set.
-If the record does not already exist or the key field is unset in $data no changes will be written.
+<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 -->
-Updates ordervalues if the dataset is {{API:PodLink|file=EPrints/DataSet|package_name=EPrints::DataSet|section=ordered|text=ordered}}.
+<!-- 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%; '>
 <span style='display:none'>User Comments</span>
@@ Line 1,276: / Line 1,241: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_exists -->
+<!-- Pod2Wiki=item_has_sequence -->
-====exists====
+====has_sequence====
-  $boolean = $db-&gt;exists( $dataset, $id )
+  $boolean = $db-&gt;has_sequence( $name )
-Return true if a record with the given primary key exists in the dataset, otherwise false.
+Returns <tt>true</tt> if a sequence of the given <tt>$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%; '>
@@ Line 1,289: / Line 1,254: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_remove -->
+<!-- Pod2Wiki=item_create_sequence -->
-====remove====
+====create_sequence====
- $success = $db-&gt;remove( $dataset, $id )
-Remove the record, index terms and order value with the key field value $id from the specified dataset.
-Returns true on success.
+ $success = $db-&gt;create_sequence( $name )
+Creates a new sequence object with <tt>$name</tt> and initialises to zero.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,304: / Line 1,267: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=head_searching_caching_and_retrieval -->
+<!-- Pod2Wiki=item_drop_sequence -->
-===Searching, Caching and Retrieval===
+====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%; '>
 <span style='display:none'>User Comments</span>
@@ Line 1,313: / Line 1,280: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_cache_exp -->
+<!-- Pod2Wiki=item_has_column -->
-====cache_exp====
+====has_column====
-  $searchexp = $db-&gt;cache_exp( $cacheid )
+  $boolean = $db-&gt;has_column( $table, $column )
-Return the serialised Search of a the cached search with id $cacheid. Return undef if the id is invalid or expired.
+Return <tt>true</tt> if the named <tt>$table</tt> has the named <tt>$column</tt> 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%; '>
@@ Line 1,326: / Line 1,293: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_cache -->
+<!-- Pod2Wiki=item_drop_column -->
-====cache====
+====drop_column====
-  $cacheid = $db-&gt;cache( $searchexp, $dataset, $srctable, [$order], [$list] )
+  $success = $db-&gt;drop_column( $table, $column )
-Create a cache of the specified search expression from the SQL table $srctable.
+Drops the named <tt>$column</tt> from the named <tt>$table</tt>.
-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.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,345: / Line 1,306: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_cache_table -->
+<!-- Pod2Wiki=item_get_primary_key -->
-====cache_table====
+====get_primary_key====
+ @columns = $db-&gt;get_primary_key( $tablename )
+Returns a list of column names that comprise the primary key for  the <tt>$tablename</tt>.
- $tablename = $db-&gt;cache_table( $id )
+Returns an empty list if no primary key exists.
-Return the SQL table used to store the cache with id $id.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,358: / Line 1,321: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_search -->
+<!-- Pod2Wiki=item_index_name -->
-====search====
+====index_name====
-  $ids = $db-&gt;search( $keyfield, $tables, $conditions, [$main_table_alias] )
+  $name = $db-&gt;index_name( $table, @cols )
-Return a reference to an array of ids - the results of the search specified by $conditions accross the tables specified in the $tables hash where keys are tables aliases and values are table names.
+Returns the name of the first index that starts with named columns  <tt>@cols</tt> in the named <tt>$table</tt>.
-If no table alias is passed then M is assumed.
+Returns <tt>undef</tt> if no index exists.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,373: / Line 1,336: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_drop_cache -->
+<!-- Pod2Wiki=item_get_index_ids -->
-====drop_cache====
+====get_index_ids====
-  $db-&gt;drop_cache( $id )
+  $ids = $db-&gt;get_index_ids( $table, $condition )
-Remove the cached search with the given id.
+Return a reference to an array of the distinct primary keys from the named SQL <tt>$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%; '>
@@ Line 1,386: / Line 1,349: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_from_cache -->
+<!-- Pod2Wiki=item_create_index -->
-====from_cache====
+====create_index====
- $foo = $db-&gt;from_cache( $dataset, $cacheid, [$offset], [$count], [$justids] )
-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.
-If $justids is true then it returns just an ref to an array of the record ids, not the objects.
+ $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.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,403: / Line 1,362: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_drop_orphan_cache_tables -->
+<!-- Pod2Wiki=item_create_unique_index -->
-====drop_orphan_cache_tables====
+====create_unique_index====
-  $c = $db-&gt;drop_orphan_cache_tables
+  $success = $db-&gt;create_unique_index( $tablename, @columns )
-Drop tables called "cacheXXX" where XXX is an integer. Returns the number of tables dropped.
+Creates a unique index over <tt>@columns</tt> for named <tt>$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%; '>
@@ Line 1,416: / Line 1,375: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_get_single -->
+<!-- Pod2Wiki=item_create_foreign_key -->
-====get_single====
+====create_foreign_key====
+ $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>.
-  $obj = $db-&gt;get_single( $dataset, $id )
+This will cause records in <tt>$table</tt> to be deleted if the equivalent  record is deleted from <tt>$main_table</tt>.
-Return a single item from the given dataset. The one with the specified id.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,429: / Line 1,390: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_get_all -->
+<!-- Pod2Wiki=item_get_tables -->
-====get_all====
+====get_tables====
+ @tables = $db-&gt;get_tables( [ $dbname ] )
+Returns a list of all the tables in the database.
- $items = $db-&gt;get_all( $dataset )
+<tt>$dbname</tt> specifies a particular database name of current connection has access to more than one database.
-Returns a reference to an array with all the items from the given dataset.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,442: / Line 1,405: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_get_cache_ids -->
+<!-- Pod2Wiki=item_has_table -->
-====get_cache_ids====
+====has_table====
-  @ids = $db-&gt;get_cache_ids( $dataset, $cachemap, $offset, $count )
+  $boolean = $db-&gt;has_table( $tablename )
-Returns a list of $count ids from $cache_id starting at $offset and in the order in the cachemap.
+Returns boolean dependent on whether a table of the <tt>$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%; '>
+<span style='display:none'>User Comments</span>
+<!-- Edit below this comment -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_create_table -->
+====create_table====
+ $success = $db-&gt;create_table( $tablename, $setkey, @fields );
+Creates a new table with <tt>$tablename</tt> based on <tt>@fields</tt>.
+The first <tt>$setkey</tt> number of fields are used for its primary key.
+<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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- 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>
 <!-- Edit below this comment -->
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_get_dataobjs -->
+<!-- Pod2Wiki=item_rename_table -->
-====get_dataobjs====
+====rename_table====
-  @dataobjs = $db-&gt;get_dataobjs( $dataset [, $id [, $id ] ] )
+  $db-&gt;rename_table( $table_from, $table_to )
-Retrieves the records in $dataset with the given $id(s). If an $id doesn't exist in the database it will be ignored.
+Renames the table named <tt>$table_from</tt> to <tt>$table_to</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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_swap_table -->
+====swap_table====
+ $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>
+<!-- Edit below this comment -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- 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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_create_archive_tables -->
+====create_archive_tables====
+ $success = $db-&gt;create_archive_tables()
+Create all the SQL tables for all datasets.
+<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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_drop_archive_tables -->
+====drop_archive_tables====
+ $db-&gt;drop_archive_tables()
+Destroy all tables used by EPrints 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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_create_version_table -->
+====create_version_table====
+ $db-&gt;create_version_table
+Make the version table (and set the only value to be the current version of EPrints).
+<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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_drop_version_table -->
+====drop_version_table====
+ $db-&gt;drop_version_table
+Drop the version 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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_has_dataset -->
+====has_dataset====
+ $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.
+This does not check that all fields are configured - see &lt;/has_field&gt;.
+<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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_has_dataset_index_tables -->
+====has_dataset_index_tables====
+ $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.
+<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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_create_dataset_tables -->
+====create_dataset_tables====
+ $success = $db-&gt;create_dataset_tables( $dataset )
+Creates all the SQL tables for the specified <tt>$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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_drop_dataset_tables -->
+====drop_dataset_tables====
+ $db-&gt;drop_dataset_tables( $dataset )
+Drops all the SQL tables for the specified <tt>$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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- 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>.
+<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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_create_dataset_ordervalues_tables -->
+====create_dataset_ordervalues_tables====
+ $success = $db-&gt;create_dataset_ordervalues_tables( $dataset )
+Creates all the ordervalues tables for the specified <tt>$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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_has_field -->
+====has_field====
+ $db-&gt;has_field( $dataset, $field )
+Returns <tt>true</tt> if <tt>$field</tt> is in the database for <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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_add_field -->
+====add_field====
+ $db-&gt;add_field( $dataset, $field, [ $force ] )
+Add <tt>$field</tt> to <tt>$dataset</tt>'s tables.
+If <tt>$force</tt> is <tt>true</tt> modify/replace an existing column. Use with  care!
+<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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_remove_field -->
+====remove_field====
+ $db-&gt;remove_field( $dataset, $field )
+Remove <tt>$field</tt> from <tt>$dataset</tt>'s tables.
+<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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_rename_field -->
+====rename_field====
+ $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>.
+Returns <tt>true</tt> if the <tt>$field</tt> is successfully renamed.
+<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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_create_counters -->
+====create_counters====
+ $success = $db-&gt;create_counters
+Create the counters used to store the highest current ID of eprints, users, etc.
+<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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_has_counter -->
+====has_counter====
+ $success = $db-&gt;has_counter( $counter )
+Returns <tt>true</tt> if <tt>$counter</tt> 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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_create_counter -->
+====create_counter====
+ $success = $db-&gt;create_counter( $name )
+Create and initialise to zero a new counter with <tt>$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%; '>
+<span style='display:none'>User Comments</span>
+<!-- Edit below this comment -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_remove_counters -->
+====remove_counters====
+ $success = $db-&gt;remove_counters
+Destroy all 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 -->
+<!-- Pod2Wiki= -->
+</div>
+<!-- Pod2Wiki=item_drop_counter -->
+====drop_counter====
+ $success = $db-&gt;drop_counter( $name )
+Destroy the counter named <tt>$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%; '>
@@ Line 1,468: / Line 1,734: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_get_values -->
+<!-- Pod2Wiki=head_user_messages -->
-====get_values====
+===User Messages===
- $foo = $db-&gt;get_values( $field, $dataset )
-Return a reference to an array of all the distinct values of the  [[API:EPrints/MetaField|EPrints::MetaField]] 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>
@@ Line 1,481: / Line 1,743: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_get_ids_by_field_values -->
+<!-- Pod2Wiki=item_save_user_message -->
-====get_ids_by_field_values====
+====save_user_message====
-  $ids = $db-&gt;get_ids_by_field_values( $field, $dataset [ %opts ] )
+  $message = $db-&gt;save_user_message( $userid, $m_type, $dom_m_data )
-Return a reference to a hash table where the keys are field value ids and the value is a reference to an array of ids.
+Save user message provided in XML DOM object <tt>$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.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,494: / Line 1,756: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=item_dequeue_events -->
+<!-- Pod2Wiki=item_get_user_messages -->
-====dequeue_events====
+====get_user_messages====
-  @events = $db-&gt;dequeue_events( $n )
+  @messages = $db-&gt;get_user_messages( $userid, %opts )
-Attempt to dequeue upto $n events. May return between 0 and $n events depending on parallel processes and how many events are remaining on the queue.
+Get the messages for a user with ID <tt>$userid</tt> and clear messages if <tt>$opt{clear}</tt> is set.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,507: / Line 1,769: @@
 <!-- Pod2Wiki= -->
 </div>
-<!-- Pod2Wiki=head_password_validation -->
+<!-- Pod2Wiki=item_clear_user_messages -->
-===Password Validation===
+====clear_user_messages====
-<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 -->
-<!-- Pod2Wiki= -->
-</div>
-<!-- Pod2Wiki=item_valid_login -->
-====valid_login====
- $real_username = $db-&gt;valid_login( $username, $password )
-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.
+ $db-&gt;clear_user_messages( $userid )
+Clear all messages for user with ID <tt>$userid</tt>.
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,533: / Line 1,784: @@
 <!-- Pod2Wiki=head_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]].
 <div style='background-color: #e8e8f; margin: 0.5em 0em 1em 0em; border: solid 1px #cce;  padding: 0em 1em 0em 1em; font-size: 80%; '>
@@ Line 1,544: / Line 1,795: @@
 <!-- Pod2Wiki=head_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%; '>
 <span style='display:none'>User Comments</span>

Difference between revisions of "API:EPrints/Database"

Latest revision as of 21:20, 4 March 2022

Contents

NAME

DESCRIPTION

Cross-database Support

Quoting SQL Values

CONSTANTS

SQL_NULL

SQL_NOT_NULL

INSTANCE VARIABLES

$self->{session}

$self->{debug}

$self->{dbh}

METHODS

Database

new

create

build_connection_string

connect

disconnect

set_debug

set_version

get_version

is_latest_version

get_server_version

get_default_charset

get_default_collation

get_driver_name

error

retry_error

duplicate_error

begin

commit

rollback

type_info

get_column_type

Basic SQL Operations

do

prepare

prepare_select

execute

update

_update

insert

insert_quoted

delete_from

count_table

clear_table

Quoting

prep_int

prep_value

prep_like_value

quote_value

quote_int

quote_binary

quote_ordervalue

quote_identifier

prepare_regexp

sql_as

sql_like

Counters

counter_current

counter_next

counter_minimum

counter_reset

next_doc_pos

Dataset Data

exists

add_record

remove

Searching, caching and object retrieval

cache_exp

cache

cache_table

cache_userid

get_cachemap

search

drop_cache

from_cache