104 lines
6.0 KiB
HTML
104 lines
6.0 KiB
HTML
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<?xml version="1.0" encoding="utf-8"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" lang="en-US" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="dc.date" scheme="iso8601" content="2005-09-19" />
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<meta name="keywords" content="WHILE statement, SQL-control-statement,
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SQL statements" />
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<title>WHILE statement</title>
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<link rel="stylesheet" type="text/css" href="ibmidwb.css" />
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<body>
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<a id="Top_Of_Page" name="Top_Of_Page"></a><!-- Java sync-link -->
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<script language = "Javascript" src = "../rzahg/synch.js" type="text/javascript"></script>
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<a name="whilestmt"></a>
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<h2 id="whilestmt"><a href="rbafzmst02.htm#ToC_1481">WHILE statement</a></h2><a id="idx3374" name="idx3374"></a><a id="idx3375" name="idx3375"></a>
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<p>The WHILE statement repeats the execution of a statement while a specified
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condition is true.</p>
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<a name="wq1904"></a>
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<h3 id="wq1904"><a href="rbafzmst02.htm#ToC_1482">Syntax</a></h3>
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<a href="rbafzmstwhilestmt.htm#syncwhile"><img src="c.gif" alt="Click to skip syntax diagram" /></a>
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<pre class="cgraphic"><span><img src="c.gif" alt="Read syntax diagram" longdesc="rbafzmstsyn425.htm"
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border="0" /></span><a href="#skipsyn-424"><img src="c.gif" alt="Skip visual syntax diagram"
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border="0" /></a>>>-+--------+--WHILE--<span class="italic">search-condition</span>--DO---------------------->
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'-<span class="italic">label:</span>-'
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.-----------------------------.
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V |
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>----<span class="italic">SQL-procedure-statement</span>-- ;-+--END WHILE--+-------+-------><
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'-<span class="italic">label</span>-'
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</pre>
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<a name="skipsyn-424" id="skipsyn-424"></a>
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<a name="syncwhile"></a>
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<h3 id="syncwhile"><a href="rbafzmst02.htm#ToC_1483">Description</a></h3>
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<dl class="parml">
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<dt class="bold"><span class="italic">label</span></dt>
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<dd>Specifies the label for the WHILE statement. If the ending
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label is specified, it must be the same as the beginning label. The label
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name cannot be the same as another label within the same scope. For more information,
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see <a href="rbafzmstsqlprocstmt.htm#psscope">Labels</a>.
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</dd>
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<dt class="bold"><span class="italic">search-condition</span></dt>
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<dd>Specifies a condition that is evaluated before each execution of the
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WHILE loop. If the condition is true, the <span class="italic">SQL-procedure-statements</span> in the WHILE loop are executed.
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</dd>
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<dt class="bold"><span class="italic">SQL-procedure-statement</span></dt>
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<dd>Specifies an SQL statement or statements to execute within the WHILE
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loop.
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</dd>
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</dl>
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<a name="wq1905"></a>
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<h3 id="wq1905"><a href="rbafzmst02.htm#ToC_1484">Example</a></h3>
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<p>This example uses a WHILE statement to iterate through FETCH and SET statements.
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While the value of SQL variable <span class="italic">v_counter</span> is less
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than half of number of employees in the department identified by the IN parameter <span class="italic">deptNumber</span>, the WHILE statement continues to perform the
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FETCH and SET statements. When the condition is no longer true, the flow of
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control leaves the WHILE statement and closes the cursor.</p>
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<pre class="xmp"><span class="bold">CREATE PROCEDURE</span> dept_median
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<span class="bold">(IN</span> deptNumber <span class="bold">SMALLINT,
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OUT</span> medianSalary <span class="bold">DECIMAL(</span>7,2<span class="bold">))</span>
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<span class="bold">LANGUAGE SQL</span>
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<span class="bold">BEGIN</span>
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<span class="bold">DECLARE</span> v_numRecords <span class="bold">INTEGER DEFAULT</span> 1;
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<span class="bold">DECLARE</span> v_counter <span class="bold">INTEGER DEFAULT</span> 0;
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<span class="bold">DECLARE</span> c1 <span class="bold">CURSOR FOR</span>
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<span class="bold">SELECT</span> salary
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<span class="bold">FROM</span> staff
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<span class="bold">WHERE</span> dept = deptNumber
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<span class="bold">ORDER BY</span> salary;
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<span class="bold">DECLARE EXIT HANDLER FOR NOT FOUND</span>
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<span class="bold">SET</span> medianSalary = 6666;
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<span class="bold">SET</span> medianSalary = 0;
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<span class="bold">SELECT COUNT(*) INTO</span> v_numRecords
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<span class="bold">FROM</span> staff
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<span class="bold">WHERE</span> dept = deptNumber;
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<span class="bold">OPEN</span> c1;
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<span class="bold">WHILE</span> v_counter < (v_numRecords/2 + 1) <span class="bold">DO</span>
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<span class="bold">FETCH</span> c1 <span class="bold">INTO</span> medianSalary;
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<span class="bold">SET</span> v_counter = v_counter +1;
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<span class="bold">END WHILE</span>;
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<span class="bold">CLOSE</span> c1;
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<span class="bold">END</span></pre>
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<hr /><br />
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