Editing Compound field (section)

== Database ==
Each sub-field within a compound field has its own table named <code><dataset>_<fieldname>_<subfieldname></code>. For example, the related URL for an EPrint (<tt>related_url</tt>) has a URL and a type, so would have tables named <tt>eprint_related_url_url</tt> and <tt>eprint_related_url_type</tt>. 

The tables in this instance have the following structure:
 eprint_related_url_url: 
   eprintid INT(11)
   pos INT(11)
   related_url_url LONGTEXT
 
 eprint_related_url_type: 
   eprintid INT(11) 
   pos INT(11)
   related_url_type VARCHAR(255)

<tt>eprintid</tt> is the ID of the eprint to which the field applies.  <tt>pos</tt> contains the position of the entry (starting at 0).  The remaining field uses the appropriate field type for the sub-field (in this case <code>LONGTEXT</code> for the [[Url field|URL]] and <code>VARCHAR(255)</code> for the type).