114 lines
5.0 KiB
HTML
114 lines
5.0 KiB
HTML
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<?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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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="Establish ODBC connections" />
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<meta name="abstract" content="Use these handle types to establish an ODBC connection." />
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<meta name="description" content="Use these handle types to establish an ODBC connection." />
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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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<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>Establish ODBC connections</title>
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</head>
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<body id="estodbcconn"><a name="estodbcconn"><!-- --></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">Establish ODBC connections</h1>
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<div><p>Use these handle types to establish an ODBC connection.</p>
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<div class="section"> <dl><dt class="dlterm">SQLAllocHandle with SQL_HANDLE_ENV as the handle type</dt>
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<dd> <ul><li>Allocates memory for an environment handle. <ul><li>Identifies storage for global information: <ul><li>Valid connection handles</li>
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<li>Current<sup>®</sup> active
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connection handles</li>
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<li>Variable type HENV</li>
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</ul>
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</li>
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</ul>
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</li>
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<li>Must be called by application prior to calling any other ODBC function.</li>
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<li>Variable type HENV is defined by ODBC in the SQL.H header file provided
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by the C programming language compiler or by the ODBC Software Development
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Kit (SDK). <p>The header file contains a type definition for a far pointer:
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</p>
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<pre> typedef void far * HENV</pre>
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</li>
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<li>In C programming language this statement is coded: <pre>SQLRETURN rc;
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HENV henv;
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rc = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);</pre>
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</li>
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<li>In Visual Basic, this statement is coded: <pre>Dim henv As long
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SQLAllocEnv(henv)</pre>
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</li>
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</ul>
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</dd>
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<dt class="dlterm">SQLAllocHandle with SQL_HANDLE_DBC as the handle type</dt>
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<dd> <ul><li>Allocates memory for an connection handle within the environment. <ul><li>Identifies storage for information about a particular connection. <ul><li>Variable type HDBC</li>
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<li>Application can have multiple connection handles.</li>
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</ul>
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</li>
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</ul>
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</li>
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<li>Application must request a connection handle prior to connecting to the
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data source.</li>
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<li>In C, this statement is coded: <pre>HDBC hdbc;
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rc = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);</pre>
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</li>
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<li>In Visual Basic, this statement is coded: <pre>Dim hdbc As long
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SQLAllocConnect(henv,hdbc)</pre>
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</li>
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</ul>
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</dd>
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<dt class="dlterm">SQLSetEnvAttr</dt>
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<dd> <ul><li>Allows an application to set attributes of an environment.</li>
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<li> To be considered an ODBC 3.x application, you must set the SQL_ATTR_ODBC_VERSION
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to SQL_OV_ODBC3 prior to allocating a connection handle.</li>
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<li>In C, this statement is coded: <pre>rc = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER) SQL_OV_ODBC3, SQL_IS_UINTEGER);</pre>
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</li>
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</ul>
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</dd>
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<dt class="dlterm">SQLConnect</dt>
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<dd> <ul><li>Loads driver and establishes a connection.</li>
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<li>Connection handle references information about the connection.</li>
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<li>Data source is coded into application. <p>In C, this statement is coded:
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</p>
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<pre>SQLCHAR source[ ] = "myDSN";
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SQLCHAR uid[ ] = "myUID";
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SQLCHAR pwd[ ] = "myPWD";
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rc = SQLConnect(hdbc, source, SQL_NTS, uid, SQL_NTS, pwd, SQL_NTS);</pre>
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<div class="note"><span class="notetitle">Note:</span> SQL_NTS
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indicates that the parameter string is a null-terminated string.</div>
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</li>
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</ul>
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</dd>
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<dt class="dlterm">SQLDriverConnect</dt>
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<dd> <ul><li>Alternative to <strong>SQLConnect</strong></li>
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<li>Allows application to override data source settings.</li>
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<li>Displays dialog boxes (optional).</li>
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</ul>
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</dd>
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</dl>
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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>
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