66 lines
4.3 KiB
HTML
66 lines
4.3 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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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="SQLFetch and SQLGetData" />
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<meta name="abstract" content="SQLGetData provides an alternative to SQLBindCol to retrieve data from the columns of a retrieved row. It can only be called after calling fetch APIs and when the array size is 1." />
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<meta name="description" content="SQLGetData provides an alternative to SQLBindCol to retrieve data from the columns of a retrieved row. It can only be called after calling fetch APIs and when the array size is 1." />
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<meta name="DC.Relation" scheme="URI" content="rzaikodbcapiinfo.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1999, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1999, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="sqlfetchgetdata" />
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<meta name="DC.Language" content="en-us" />
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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>SQLFetch and SQLGetData</title>
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</head>
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<body id="sqlfetchgetdata"><a name="sqlfetchgetdata"><!-- --></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">SQLFetch and SQLGetData</h1>
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<div><p><strong>SQLGetData</strong> provides an alternative to <strong>SQLBindCol</strong> to
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retrieve data from the columns of a retrieved row. It can only be called after
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calling fetch APIs and when the array size is 1.</p>
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<div class="section"></div>
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<div class="section"><p>As a general rule, <strong>SQLBindCol</strong> is preferable to <strong>SQLGetData</strong>.
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There is less performance overhead; you need to run <strong>SQLBindCol</strong> only
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once rather than after every fetch. However, there are special considerations
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for using <strong>SQLBindCol</strong> in Visual Basic.</p>
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</div>
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<div class="section"><p>Visual Basic moves character strings to different locations to
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conserve memory. If a string variable is bound to a column, the memory that
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is referenced by a subsequent <strong>SQLFetch</strong> may not place the data in the
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desired variable. It is likely that a <strong>General Protection Fault</strong> will
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result. A similar problem can occur with <strong>SQLBindParameter</strong>.</p>
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</div>
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<div class="section"><p>Using strings in Visual Basic is not recommended. One way to avoid
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this problem is to use <strong>byte arrays</strong>. Byte arrays are of a fixed size
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and are not subject to movement in memory.</p>
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</div>
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<div class="section"><p>Another circumvention is to employ Windows<sup>®</sup> memory allocation API functions
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that are documented in the <a href="http://msdn.microsoft.com/library/default.asp">Microsoft<sup>®</sup> Development Library</a> Knowledge
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Base. However, this method involves some difficult programming that is not
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totally transportable between Windows 3.1 and later releases.</p>
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</div>
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<div class="section"><p>Using <strong>SQLGetData</strong> rather than <strong>SQLBindCol</strong> and <strong>SQLParamData</strong> and <strong>SQLPutData</strong> in
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conjunction with <strong>SQLBindParameter</strong> produce software that is more in
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keeping with Visual Basic. However, this method involves some difficult programming.</p>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzaikodbcapiinfo.htm" title="Identify the files required to build an ODBC application.">Files required to build an ODBC application</a></div>
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</div>
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</div>
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</body>
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</html> |