67 lines
4.0 KiB
HTML
67 lines
4.0 KiB
HTML
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Constraint states" />
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<meta name="abstract" content="A file can be in one of three constraint states. In two of the states, the constraint can be enabled or disabled." />
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<meta name="description" content="A file can be in one of three constraint states. In two of the states, the constraint can be enabled or disabled." />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<title>Constraint states</title>
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</head>
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<body id="rbaforzahfrcu"><a name="rbaforzahfrcu"><!-- --></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">Constraint states</h1>
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<div><p>A file can be in one of three constraint states. In two of the
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states, the constraint can be enabled or disabled. </p>
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<div class="p"><ul><li><strong>Non-constraint relationship state</strong>. No referential constraint exists
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for a file in this state. If a constraint relationship once existed for the
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file, all information about it has been removed.</li>
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<li><strong>Defined state</strong>. A constraint relationship is defined between a dependent
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and a parent file. It is not necessary to create the member in either file
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to define a constraint relationship. In the defined state, the constraint
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can be: <ul><li>Defined and enabled. A defined and enabled constraint relationship is
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for definition purposes only. The rules for the constraint are not enforced.
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A constraint in this state remains enabled when it goes to the established
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state.</li>
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<li>Defined and disabled. A defined constraint relationship that
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is disabled is for definition purposes only. The rules for the constraint
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are not enforced. A constraint in this state remains disabled when it goes
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to the established state.</li>
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</ul>
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</li>
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<li><strong>Established state</strong>. The dependent file has a constraint relationship
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with the parent file. A constraint will be established only if the attributes
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match between the foreign and parent key. Members must exist for both files.
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In the established state, the constraint can be: <ul><li>Established and enabled. An established constraint relationship that is
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enabled causes the database to enforce referential integrity.</li>
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<li>Established and disabled. An established constraint relationship that
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is disabled directs the database to not enforce referential integrity.</li>
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</ul>
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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="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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