75 lines
4.5 KiB
HTML
75 lines
4.5 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Details: Specify referential constraint delete rules" />
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<meta name="abstract" content="This topic lists the possible values for the DLTRULE parameter. The delete rule specifies the action the system takes when you delete a parent key value. The delete rule does not affect null parent key values." />
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<meta name="description" content="This topic lists the possible values for the DLTRULE parameter. The delete rule specifies the action the system takes when you delete a parent key value. The delete rule does not affect null parent key values." />
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<meta name="DC.Relation" scheme="URI" content="rbaforzahfrck.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="rbaforzahfrcl" />
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<meta name="DC.Language" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Details: Specify referential constraint delete rules</title>
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</head>
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<body id="rbaforzahfrcl"><a name="rbaforzahfrcl"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Details: Specify referential constraint delete rules</h1>
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<div><p>This topic lists the possible values for the DLTRULE parameter.
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The delete rule specifies the action the system takes when you delete a parent
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key value. The delete rule does not affect null parent key values. </p>
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<div class="p"><ul><li>*NOACTION (the default value) <ul><li>Record deletion in a parent file will not occur if the parent key value
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has a matching foreign key value.</li>
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</ul>
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</li>
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<li>*CASCADE <ul><li>Record deletion in a parent file causes records in the dependent file
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to be deleted when the parent key value matches the foreign key value.</li>
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</ul>
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</li>
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<li>*SETNULL <ul><li>Record deletion in a parent file updates those records in the dependent
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file where the value of the parent non-null key matches the foreign key value.
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For those dependent records that meet the preceding criteria, all null-capable
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fields in the foreign key are set to null. Foreign key fields with the non-null
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attribute are not updated.</li>
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</ul>
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</li>
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<li>*SETDFT <ul><li>Record deletion in a parent file updates those records in the dependent
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file where the value of the parent non-null key matches the foreign key value.
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For those dependent records that meet the preceding criteria, the foreign
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key field or fields are set to their corresponding default values.</li>
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</ul>
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</li>
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<li>*RESTRICT <ul><li>Record deletion in a parent file will not occur if the parent key value
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has a matching foreign key value.</li>
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</ul>
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<div class="note"><span class="notetitle">Note:</span> The system enforces a delete *RESTRICT rule immediately when the
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deletion is attempted. The system enforces other constraints at the logical
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end of the operation. The operation, in the case of other constraints, includes
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any trigger programs that are run before or after the delete operation. It
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is possible for a trigger program to correct a potential referential integrity
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violation. For example, a trigger program can add a parent record if one does
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not exist. The *RESTRICT rule does not prevent the violation.</div>
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</li>
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</ul>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rbaforzahfrck.htm" title="Referential constraints allow you to specify rules that you want the system to enforce when you delete or update records.">Specify referential constraint rules</a></div>
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</div>
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</div>
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</body>
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</html>
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