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<h1 class="topictitle1">Example: Square of a number UDF</h1>
<div><p>In this example, suppose that you want a function that returns
the square of a number.</p>
<div class="section"><p>The query statement is:</p>
<pre><strong>SELECT</strong> SQUARE(myint) <strong>FROM</strong> mytable</pre>
</div>
<div class="section"> <div class="note"><span class="notetitle">Note:</span> By using the code examples, you agree to the terms of the <a href="codedisclaimer.htm">Code license and disclaimer information</a>.</div>
</div>
<div class="section"><p>The following examples show how to define the UDF several different
ways.</p>
</div>
<div class="section"><h4 class="sectiontitle">Use an SQL function</h4><p>The CREATE FUNCTION statement:</p>
<pre><strong>CREATE FUNCTION</strong> SQUARE( inval <strong>INT</strong>) <strong>RETURNS INT</strong>
<strong>LANGUAGE SQL
SET OPTION DBGVIEW=*SOURCE
BEGIN
RETURN</strong>(inval*inval);
<strong>END</strong></pre>
<p>This creates an SQL function that you can debug.</p>
</div>
<div class="section"><h4 class="sectiontitle">Use an external function, parameter style SQL</h4><p>The
CREATE FUNCTION statement: </p>
<pre><strong>CREATE FUNCTION</strong> SQUARE(<strong>INT</strong>) <strong>RETURNS INT CAST FROM FLOAT</strong>
<strong>LANGUAGE C</strong>
<strong>EXTERNAL NAME</strong> 'MYLIB/MATH(SQUARE)'
<strong>DETERMINISTIC
NO SQL
NO EXTERNAL ACTION
PARAMETER STYLE SQL
ALLOW PARALLEL</strong> </pre>
<p>The code: </p>
<pre>void SQUARE(int *inval,
double *outval,
short *inind,
short *outind,
char *sqlstate,
char *funcname,
char *specname,
char *msgtext)
{
if (*inind<0)
*outind=-1;
else
{
*outval=*inval;
*outval=(*outval)*(*outval);
*outind=0;
}
return;
}</pre>
<p>To create the external service program so it can be debugged: </p>
<pre>CRTCMOD MODULE(mylib/square) DBGVIEW(*SOURCE)
CRTSRVPGM SRVPGM(mylib/math) MODULE(mylib/square)
EXPORT(*ALL) ACTGRP(*CALLER)</pre>
</div>
<div class="section"><h4 class="sectiontitle">Use an external function, parameter style GENERAL</h4><p>The
CREATE FUNCTION statement:</p>
<pre><strong>CREATE FUNCTION</strong> SQUARE(<strong>INT</strong>) <strong>RETURNS INT CAST FROM FLOAT</strong>
<strong>LANGUAGE C
EXTERNAL NAME</strong> 'MYLIB/MATH(SQUARE)'
<strong>DETERMINISTIC
NO SQL
NO EXTERNAL ACTION
PARAMETER STYLE GENERAL
ALLOW PARALLEL</strong> </pre>
<p>The code:</p>
<pre>double SQUARE(int *inval)
{
double outval;
outval=*inval;
outval=outval*outval;
return(outval);
}</pre>
<p>To create the external service program so it can be debugged: </p>
<pre>CRTCMOD MODULE(mylib/square) DBGVIEW(*SOURCE)
CRTSRVPGM SRVPGM(mylib/math) MODULE(mylib/square)
EXPORT(*ALL) ACTGRP(*CALLER)</pre>
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<div class="familylinks">
<div class="parentlink"><strong>Parent topic:</strong> <a href="rbafyuwexam.htm" title="These examples show how to implement UDF code by using SQL functions and external functions.">Examples: UDF code</a></div>
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