84 lines
4.9 KiB
HTML
84 lines
4.9 KiB
HTML
<?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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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="Define a UDT" />
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<meta name="abstract" content="UDTs are defined with a CREATE DISTINCT TYPE statement." />
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<meta name="description" content="UDTs are defined with a CREATE DISTINCT TYPE statement." />
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<meta name="DC.subject" content="UDTs (User-defined types), defining a UDT, CREATE DISTINCT TYPE statement, to define a UDT" />
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<meta name="DC.Relation" scheme="URI" content="rbafyuddt.htm" />
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<meta name="DC.Relation" scheme="URI" content="rbafymoney.htm" />
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<meta name="DC.Relation" scheme="URI" content="../db2/rbafzmstcrtudt.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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<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>Define a UDT</title>
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</head>
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<body id="rbafydefudt"><a name="rbafydefudt"><!-- --></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">Define a UDT</h1>
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<div><p>UDTs are defined with a CREATE DISTINCT TYPE statement. </p>
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<div class="section"><p>For the CREATE DISTINCT TYPE statement, note that: </p>
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</div>
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<div class="section"> <ol><li>The name of the new UDT can be a qualified or an unqualified name.</li>
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<li>The source type of the UDT is the type used by the system to internally
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represent the UDT. For this reason, it must be a built-in data type. Previously
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defined UDTs cannot be used as source types of other UDTs. </li>
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</ol>
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</div>
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<div class="section"><p>As part of a UDT definition, the system always generates cast
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functions to: </p>
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</div>
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<div class="section"> <ul><li>Cast from the UDT to the source type, using the standard name of the
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source type. For example, if you create a distinct type based on FLOAT, the
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cast function called DOUBLE is created. </li>
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<li>Cast from the source type to the UDT. </li>
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</ul>
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</div>
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<div class="section"><p>These functions are important for the manipulation of UDTs in
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queries.</p>
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</div>
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<div class="section"><p>The function path is used to resolve any references to an unqualified
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type name or function, except if the type name or function is the main object
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of a CREATE, DROP, or COMMENT ON statement.</p>
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</div>
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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="rbafymoney.htm">Example: Money</a></strong><br />
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In this example, suppose you are writing applications that need
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to handle different currencies and want to ensure that DB2<sup>®</sup> does not allow these currencies to be
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compared or manipulated directly with one another in queries.</li>
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<li class="ulchildlink"><strong><a href="rbafyresume.htm">Example: Resume</a></strong><br />
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In this example, suppose you want to keep the application forms that are filled out by applicants to your company in a table and you are going to use functions to extract the information from these forms.</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="rbafyuddt.htm" title="A user-defined distinct type is a mechanism that allows you to extend DB2 capabilities beyond the built-in data types available.">Use user-defined distinct types (UDT)</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="rbafyusquref.htm" title="If you use a qualified function reference, you restrict the search for a matching function to that schema.">Use qualified function reference</a></div>
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</div>
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<div class="relinfo"><strong>Related information</strong><br />
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<div><a href="../db2/rbafzmstcrtudt.htm">CREATE DISTINCT TYPE statement</a></div>
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</div>
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</div>
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</body>
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</html> |