67 lines
5.1 KiB
HTML
67 lines
5.1 KiB
HTML
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<meta name="DC.Title" content="Use UDFs in SQL statements" />
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<meta name="abstract" content="Scalar and column UDFs can be called within an SQL statement almost everywhere that an expression is valid. Table UDFs can be called in the FROM clause of a SELECT. There are a few restrictions of UDF usage, however." />
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<meta name="description" content="Scalar and column UDFs can be called within an SQL statement almost everywhere that an expression is valid. Table UDFs can be called in the FROM clause of a SELECT. There are a few restrictions of UDF usage, however." />
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<meta name="DC.subject" content="UDFs (User-defined functions), calling, examples of invocations" />
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<title>Use UDFs in SQL statements</title>
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</head>
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<body id="rbafyudfuudf"><a name="rbafyudfuudf"><!-- --></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">Use UDFs in SQL statements</h1>
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<div><p>Scalar and column UDFs can be called within an SQL statement almost
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everywhere that an expression is valid. Table UDFs can be called in the FROM
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clause of a SELECT. There are a few restrictions of UDF usage, however.</p>
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<div class="section"><ul><li>UDFs and system generated functions cannot be specified in check constraints.
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Check constraints also cannot contain references to some built-in functions
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that are implemented by the system as UDFs. </li>
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<li>External UDFs, SQL UDFS and the built-in functions DLVALUE, DLURLPATH,
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DLURLPATHONLY, DLURLSCHEME, DLURLCOMPLETE, and DLURLSERVER cannot be referenced
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in an ORDER BY or GROUP BY clause, unless the SQL statement is read-only and
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allows temporary processing (ALWCPYDTA(*YES) or (*OPTIMIZE)).</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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<ul class="ullinks">
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<li class="ulchildlink"><strong><a href="rbafyuseparameter.htm">Use parameter markers or the NULL value as function arguments</a></strong><br />
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An important restriction involves both parameter markers and the NULL value.</li>
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<li class="ulchildlink"><strong><a href="rbafyusquref.htm">Use qualified function reference</a></strong><br />
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If you use a qualified function reference, you restrict the search for a matching function to that schema.</li>
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<li class="ulchildlink"><strong><a href="rbafyuseunqualified.htm">Use unqualified function reference</a></strong><br />
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You can use an unqualified function reference instead of a qualified function reference. In this case, DB2's search for a matching function normally uses the function path to qualify the reference.</li>
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<li class="ulchildlink"><strong><a href="rbafysummary.htm">Summary of function references</a></strong><br />
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For both qualified and unqualified function references, the function selection algorithm looks at all the applicable functions, both built-in and user-defined functions, that have the given name, the same number of defined parameters as argument, and each parameter identical to or promotable from the type of the corresponding argument.</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="rbafyudf.htm" title="In writing SQL applications, you can implement some actions or operations as a UDF or as a subroutine in your application: Although it may appear easier to implement new operations as subroutines in your application, you might want to consider the advantages of using a UDF instead.">Use user-defined functions (UDFs)</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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