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<?xml version="1.0" encoding="UTF-8"?>
<helpdocument version="1.0">
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<meta>
<topic id="textsharedexplorerdatabase05020000xml" indexer="include">
<title id="tit" xml-lang="en-US">Relations</title>
<filename>/text/sdatabase/05020000.xhp</filename>
</topic>
</meta>
<body>
<section id="relations">
<bookmark xml-lang="en-US" branch="hid/DBACCESS_HID_CTL_RELATIONTAB" id="bm_id3153345" localize="false"/>
<h1 id="hd_id3153323"><link href="text/sdatabase/05020000.xhp">Relations</link></h1>
<bookmark xml-lang="en-US" branch="index" id="bm_id3146957"><bookmark_value>relational databases (Base)</bookmark_value>
</bookmark><comment>mw added "(Base)"</comment>
<paragraph role="paragraph" id="par_id3146957" xml-lang="en-US">This command opens the <emph>Relation Design </emph>window, which allows you to define relationships between various database tables.</paragraph>
</section>
<paragraph role="paragraph" id="par_id3154823" xml-lang="en-US"><ahelp hid="HID_CTL_RELATIONTAB">Here you can link together tables from the current database through common data fields.</ahelp> Click the <emph>New Relation</emph> icon to create the relationships, or simply drag-and-drop with the mouse.</paragraph>
<section id="howtoget">
<embed href="text/shared/00/00000450.xhp#relationen"/>
</section>
<note id="par_id3145316">This function is only available if you are working with a relational database.</note>
<paragraph role="paragraph" id="par_id3149235" xml-lang="en-US">When you choose <emph>Tools - Relationships</emph>, a window opens in which all the existing relationships between the tables of the current database are shown. If no relationships have been defined, or if you want to relate other tables of the database to each other, then click on the <emph>Add Tables</emph> icon. The <link href="text/shared/02/14020100.xhp">Add Tables</link> dialog opens in which you can select the tables with which to create a relation.</paragraph>
<embed href="text/shared/00/00000450.xhp#syinsert_table"/>
<note id="par_id3152812">If the <emph>Relation Design</emph> window is open, the selected tables cannot be modified, even in Table Design mode. This ensures that tables are not changed while the relations are being created.</note>
<paragraph role="paragraph" id="par_id3150541" xml-lang="en-US">The selected tables are shown in the top area of the relation design view. You can close a table window through the context menu or with the Delete key.</paragraph>
<embed href="text/sdatabase/02010100.xhp#change_display"/>
<bookmark xml-lang="en-US" branch="index" id="bm_id3148922"><bookmark_value>primary keys;inserting (Base)</bookmark_value>
<bookmark_value>keys;primary keys (Base)</bookmark_value>
<bookmark_value>external keys (Base)</bookmark_value>
</bookmark><comment>mw added "(Base)" to all entries</comment>
<h2 id="hd_id3148922">Primary key and foreign keys</h2>
<paragraph role="paragraph" id="par_id3149168" xml-lang="en-US">If you want to define a relation among the various tables, you should enter a <link href="text/shared/00/00000005.xhp#primary_key">primary key</link> that uniquely identifies a data field of an existing table. You can refer to the primary key from other tables to access the data of this table. All data fields referring to this primary key will be identified as a foreign key.</paragraph>
<paragraph role="paragraph" id="par_id3147085" xml-lang="en-US">All data fields referring to a primary key will be identified in the table window by a small key symbol.</paragraph>
<h2 id="hd_id3153193">Define relations</h2>
<bookmark xml-lang="en-US" branch="index" id="bm_id3155430"><bookmark_value>relations; creating and deleting (Base)</bookmark_value>
</bookmark><comment>mw added "(Base)"</comment>
<paragraph role="paragraph" id="par_id3155430" xml-lang="en-US">All existing relations are shown in the relations windows by a line that connects the primary and foreign key fields. You can add a relation by using drag-and-drop to drop the field of one table onto the field of the other table. A relation is removed again by selecting it and pressing the Delete key.</paragraph>
<paragraph role="paragraph" id="par_id3149984" xml-lang="en-US">Alternatively, you can also click the <emph>New Relation</emph> icon in the top area of the relation field and define the relation between two tables in the <link href="text/sdatabase/05020100.xhp"><emph>Relations</emph></link> dialog.</paragraph>
<embed href="text/shared/00/00000450.xhp#synew_relation"/>
<warning id="par_id3153093">If you use $[officename] as the front-end for a relational database, the creation and deletion of relationships is not placed in an intermediate memory by $[officename], but is forwarded directly to the database.</warning>
<paragraph role="paragraph" id="par_id3155856" xml-lang="en-US">By double-clicking a connection line, you can assign certain properties to the relation. The <emph>Relations </emph>dialog opens.</paragraph>
</body>
</helpdocument>
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