84 lines
6.1 KiB
HTML
84 lines
6.1 KiB
HTML
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="Register UDFs" />
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<meta name="abstract" content="A UDF must be registered in the database before the function can be recognized and used by SQL." />
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<meta name="description" content="A UDF must be registered in the database before the function can be recognized and used by SQL." />
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<meta name="DC.subject" content="UDFs (User-defined functions), registering UDFs, examples of registering, CREATE FUNCTION statement, to register a UDF" />
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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>Register UDFs</title>
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</head>
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<body id="rbafyudfdudf"><a name="rbafyudfdudf"><!-- --></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">Register UDFs</h1>
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<div><p>A UDF must be registered in the database before the function can
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be recognized and used by SQL.</p>
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<div class="section"><p>The statement allows you to specify the language and name of the
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program, along with options such as DETERMINISTIC, ALLOW PARALLEL, and RETURNS
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NULL ON NULL INPUT. These options help to more specifically identify to the
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database the intention of the function and how calls to the database can be
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optimized.</p>
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</div>
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<div class="section"><p>You should register an external UDF after you have written and
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completely tested the actual code. It is possible to define the UDF before
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actually writing it. However, to avoid any problems with running your UDF,
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you are encouraged to write and test it extensively before registering it.</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="rbafyudfcfx1.htm">Example: Exponentiation</a></strong><br />
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In this example, suppose you have written an external UDF to perform exponentiation of floating point values, and want to register it in the MATH schema.</li>
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<li class="ulchildlink"><strong><a href="rbafyudfcfx2.htm">Example: String search</a></strong><br />
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Suppose you have written a UDF to look for the existence of a given short string, passed as an argument, within a given CLOB value that is also passed as an argument. The UDF returns the position of the string within the CLOB if it finds the string, or zero if it does not.</li>
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<li class="ulchildlink"><strong><a href="rbafyudfcfxa.htm">Example: BLOB string search</a></strong><br />
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In this example, you want the FINDSTRING function to work on BLOBs as well as on CLOBs. To do this, you define another FINDSTRING taking BLOB as the first parameter:</li>
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<li class="ulchildlink"><strong><a href="rbafyudfcfx3.htm">Example: String search over UDT</a></strong><br />
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Assume that you are satisfied with the FINDSTRING functions from the BLOB string search, but now you have defined a distinct type BOAT with source type BLOB.</li>
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<li class="ulchildlink"><strong><a href="rbafyudfcfx5.htm">Example: AVG over a UDT</a></strong><br />
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This example implements the AVG column function over the CANADIAN_DOLLAR distinct type.</li>
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<li class="ulchildlink"><strong><a href="rbafyudfcfx6.htm">Example: Counting</a></strong><br />
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Your simple counting function returns a <samp class="codeph">1</samp> the
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first time and increments the result by one each time it is called. This function
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takes no SQL arguments, and by definition it is a NOT DETERMINISTIC function
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since its answer varies from call to call.</li>
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<li class="ulchildlink"><strong><a href="rbafyudfcfx7.htm">Example: Table function returning document IDs</a></strong><br />
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In this example, you have written a table function that returns a row consisting of a single document identifier column for each known document in your text management system that matches a given subject area (the first parameter) and contains the given string (second parameter).</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="rbafywudfextern.htm" title="You can write the executable code of a UDF in a language other than SQL.">Write UDFs as external functions</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/rbafzmstcreatef.htm">CREATE FUNCTION statement</a></div>
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</div>
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</div>
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</body>
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