53 lines
3.6 KiB
HTML
53 lines
3.6 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 name="security" content="public" />
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<meta name="Robots" content="index,follow" />
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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="Verify referential constraints" />
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<meta name="abstract" content="The system automatically verifies the validity of a referential constraint when you add the constraint with the Add Physical File Constraint (ADDPFCST) command. The system verifies that every non-null value in the foreign key matches a corresponding value in the parent key." />
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<meta name="description" content="The system automatically verifies the validity of a referential constraint when you add the constraint with the Add Physical File Constraint (ADDPFCST) command. The system verifies that every non-null value in the foreign key matches a corresponding value in the parent key." />
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<meta name="DC.Relation" scheme="URI" content="rbaforzahfrca.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="rbaforzahfrco" />
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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>Verify referential constraints</title>
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</head>
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<body id="rbaforzahfrco"><a name="rbaforzahfrco"><!-- --></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">Verify referential constraints</h1>
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<div><p>The system automatically verifies the validity of a referential
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constraint when you add the constraint with the Add Physical File Constraint
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(ADDPFCST) command. The system verifies that every non-null value in the foreign
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key matches a corresponding value in the parent key.</p>
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<p>If the verification is successful, the constraint rules are enforced on
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subsequent accesses by a user or an application program. An unsuccessful verification
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causes the constraint to be marked as check pending. If the constraint is
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added with the ADDPFCST command, it will be in check pending but disabled
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state.</p>
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<div class="note"><span class="notetitle">Note:</span> It is not uncommon to add a referential constraint to existing files
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that contain large amounts of data. The ADDPFCST command can take several
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hours to complete when a very large number of records are involved. The add
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process places an exclusive lock on the files. You should take this time factor
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and file availability into consideration before you add a referential
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constraint.</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="rbaforzahfrca.htm" title="These topics discuss how to use referential constraints in your database to ensure that it contains only valid data.">Ensure data integrity with referential constraints</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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