73 lines
5.3 KiB
HTML
73 lines
5.3 KiB
HTML
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<meta name="DC.Title" content="Control the integrity of your database with constraints" />
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<meta name="abstract" content="A constraint is a restriction or limitation placed on a file to ensure that the data in your database remains consistent as you add, change, and remove records. These topics describe how to use constraints to ensure data consistency." />
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<title>Control the integrity of your database with constraints</title>
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<body id="rbaforzahfcoa"><a name="rbaforzahfcoa"><!-- --></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">Control the integrity of your database with constraints</h1>
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<div><p>A <em>constraint</em> is a restriction or limitation
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placed on a file to ensure that the data in your database remains consistent
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as you add, change, and remove records. These topics describe how to use constraints
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to ensure data consistency.</p>
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<div class="p"> <ul><li>Unique constraints and primary key constraints let you create enforced
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unique keys for a physical file beyond the file access path. </li>
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<li> Check constraints provide another check for the validity of your data
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by testing the data in an expression. </li>
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</ul>
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</div>
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<p>Primary key and unique constraints can be used as the parent key when adding
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a referential constraint.</p>
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</div>
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<div>
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<ul class="ullinks">
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<li class="ulchildlink"><strong><a href="rbaforzahfcod.htm">Set up constraints for your database</a></strong><br />
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You can use physical file constraints to control the integrity
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of the data that is maintained in your database. You can also add constraints
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using iSeries™ Navigator.</li>
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<li class="ulchildlink"><strong><a href="rbaforzahfcof.htm">Remove unique, primary key, or check constraints</a></strong><br />
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The Remove Physical File Constraint (RMVPFCST) command allows you to remove a physical file constraint. The full effects of the command depend on the type of constraint you remove and how it is used.</li>
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<li class="ulchildlink"><strong><a href="rbaforzahfcoh.htm">Work with a group of constraints</a></strong><br />
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The Work with Physical File Constraints (WRKPFCST) command allows you to display and work with a list of the constraints.</li>
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<li class="ulchildlink"><strong><a href="rbaforzahfcob.htm">Unique constraints</a></strong><br />
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Unique constraints act as controls in a database to ensure that rows are unique.</li>
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<li class="ulchildlink"><strong><a href="rbaforzahfcoc.htm">Primary key constraints</a></strong><br />
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A primary key constraint is a unique key with special attributes that make the key the primary access path for the file.</li>
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<li class="ulchildlink"><strong><a href="rbaforzahfcon.htm">Check constraints</a></strong><br />
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You use check constraints to maintain limits on field values so that they conform to your database requirements.</li>
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</ul>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rbafomanage.htm" title="These topics discuss how to maintain control of database files on your system by managing the files, their descriptions and attributes. Information about how to maintain control over your data to protect it from loss, how to ensure data integrity with constraints, and how to set up trigger events when the data changes is included.">Manage database files</a></div>
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