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<?xml version="1.0" encoding="UTF-8"?>
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<helpdocument version="1.0">
<meta>
<topic id="textsharedexplorerdatabase05020100xml" indexer="exclude" status="PUBLISH">
<title id="tit" xml-lang="en-US">Relations</title>
<filename>/text/sdatabase/05020100.xhp</filename>
</topic>
<history>
<created date="2003-10-31T00:00:00">Sun Microsystems, Inc.</created>
</history>
</meta>
<body>
<bookmark xml-lang="en-US" branch="hid/.uno:DBAddRelation" id="bm_id3155150" localize="false"/>
<bookmark xml-lang="en-US" branch="hid/dbaccess/ui/relationdialog/RelationDialog" id="bm_id3155151" localize="false"/>
<bookmark xml-lang="en-US" branch="index" id="bm_id3150499"><bookmark_value>relations; properties (Base)</bookmark_value>
<bookmark_value>key fields for relations (Base)</bookmark_value>
<bookmark_value>cascading update (Base)</bookmark_value>
</bookmark><comment>mw added "(Base)" to all entries</comment>
<h1 id="hd_id3150445">Relations</h1>
<paragraph role="paragraph" id="par_id3150499" xml-lang="en-US"><ahelp hid=".uno:DBAddRelation">Allows you to define and edit a relation between two tables.</ahelp></paragraph>
<section id="howtoget">
<embed href="text/shared/00/00000450.xhp#relationen"/>
</section>
<note id="par_id3155136">The update and delete options are only available if they are supported by the database used.</note>
<h2 id="hd_id3155341">Tables involved</h2>
<paragraph role="paragraph" id="par_id3153880" xml-lang="en-US"><ahelp hid="dbaccess/ui/relationdialog/table2">This is where the two related tables are listed.</ahelp> If you create a new relation, you can select one table from each of the combo boxes in the top part of the dialog.</paragraph>
<paragraph role="paragraph" id="par_id3154047" xml-lang="en-US">If you opened the <emph>Relations</emph> dialog for an existing relation by double-clicking the connection lines in the Relation window, then the tables involved in the relation cannot be modified.</paragraph>
<bookmark xml-lang="en-US" branch="hid/dbaccess/ui/joindialog/relations" id="bm_id3153716" localize="false"/>
<h2 id="hd_id3153822">Key fields</h2>
<paragraph role="paragraph" id="par_id3159157" xml-lang="en-US"><ahelp hid="dbaccess/ui/joindialog/relations">Defines the key fields for the relation.</ahelp></paragraph>
<bookmark xml-lang="en-US" branch="hid/dbaccess/ui/relationdialog/relations" id="bm_id3153543" localize="false"/>
<paragraph role="paragraph" id="par_id3149235" xml-lang="en-US"><ahelp hid="dbaccess/ui/relationdialog/table2">The names of the tables selected for the link appear here as column names.</ahelp> If you click a field, you can use the arrow buttons to select a field from the table. Each relation is written in a row.</paragraph>
<h2 id="hd_id3145609">Update options</h2>
<paragraph role="paragraph" id="par_id3153061" xml-lang="en-US">Here you can select options that take effect when there are changes to a primary key field.</paragraph>
<h3 id="hd_id3149046">No action</h3>
<paragraph role="paragraph" id="par_id3152360" xml-lang="en-US"><ahelp hid="dbaccess/ui/relationdialog/addaction">Specifies that any change made to a primary key does not affect other external key fields.</ahelp></paragraph>
<h3 id="hd_id3148664">Updating cascade</h3>
<paragraph role="paragraph" id="par_id3154073" xml-lang="en-US"><ahelp hid="dbaccess/ui/relationdialog/addcascade">Updates all the external key fields if the value of the corresponding primary key has been modified (Cascading Update).</ahelp></paragraph>
<h3 id="hd_id3145171">Set null</h3>
<paragraph role="paragraph" id="par_id3154123" xml-lang="en-US"><ahelp hid="dbaccess/ui/relationdialog/addnull"> If the corresponding primary key has been modified, use this option to set the "IS NULL" value to all external key fields. IS NULL means that the field is empty.</ahelp></paragraph>
<h3 id="hd_id3150448">Set default</h3>
<paragraph role="paragraph" id="par_id3151041" xml-lang="en-US"><ahelp hid="dbaccess/ui/relationdialog/adddefault"> If the corresponding primary key has been modified, use this option to set a default value to all external key fields.</ahelp> During the creation of the corresponding table, the default value of an external key field will be defined when you assign the field properties.</paragraph>
<h2 id="hd_id3125863">Delete options</h2>
<paragraph role="paragraph" id="par_id3153193" xml-lang="en-US">Here you can select options that take effect when a primary key field is deleted.</paragraph>
<h3 id="hd_id3159252">No action</h3>
<paragraph role="paragraph" id="par_id3145785" xml-lang="en-US"><ahelp hid="dbaccess/ui/relationdialog/delaction">Specifies that the deletion of a primary key will not have any effect on other external key fields.</ahelp></paragraph>
<h3 id="hd_id3154146">Delete cascade</h3>
<paragraph role="paragraph" id="par_id3155309" xml-lang="en-US"><ahelp hid="dbaccess/ui/relationdialog/delcascade">Specifies that all external key fields will be deleted if you delete the corresponding primary key field.</ahelp></paragraph>
<warning id="par_id3153140">When you delete a primary key field with the<emph> Delete cascade </emph>option, all records from other tables that have this key as their foreign key are also deleted. Use this option with great care; it is possible that a major portion of the database can be deleted.</warning>
<h3 id="hd_id3152596">Set null</h3>
<paragraph role="paragraph" id="par_id3153363" xml-lang="en-US"><ahelp hid="dbaccess/ui/relationdialog/delnull">If you delete the corresponding primary key, the "IS NULL" value will be assigned to all external key fields.</ahelp></paragraph>
<h3 id="hd_id3145272">Set Default</h3>
<paragraph role="paragraph" id="par_id3154320" xml-lang="en-US"><ahelp hid="dbaccess/ui/relationdialog/deldefault">If you delete the corresponding primary key, a set value will be set to all external key fields.</ahelp></paragraph>
</body>
</helpdocument>
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