198 lines
8.9 KiB
HTML
198 lines
8.9 KiB
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.Title" content="SQLAllocEnv - Allocate environment handle" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1999, 2006" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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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>SQLAllocEnv - Allocate environment handle</title>
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</head>
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<body id="rzadpfnaenv"><a name="rzadpfnaenv"><!-- --></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">SQLAllocEnv - Allocate environment handle</h1>
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<div><div class="section"><h4 class="sectiontitle">Purpose</h4> <p><samp class="codeph">SQLAllocEnv()</samp> allocates
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an environment handle and associated resources.</p>
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<p>An application must
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call this function before <samp class="codeph">SQLAllocConnect()</samp> or any other DB2<sup>®</sup> UDB
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CLI functions. The <em>henv</em> value is passed in all later function calls
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that require an environment handle as input.</p>
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</div>
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<div class="section"><h4 class="sectiontitle">Syntax</h4> <pre>SQLRETURN SQLAllocEnv (SQLHENV *phenv);</pre>
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</div>
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<div class="section"><h4 class="sectiontitle">Function arguments</h4>
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" width="100%" frame="hsides" border="1" rules="all"><caption>Table 1. SQLAllocEnv arguments</caption><thead align="left"><tr><th align="left" valign="bottom" width="20%" id="d0e64">Data type</th>
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<th align="left" valign="bottom" width="20%" id="d0e66">Argument</th>
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<th align="left" valign="bottom" width="20%" id="d0e68">Use</th>
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<th align="left" valign="bottom" width="40%" id="d0e70">Description</th>
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</tr>
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</thead>
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<tbody><tr><td align="left" valign="top" width="20%" headers="d0e64 ">SQLHENV *</td>
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<td align="left" valign="top" width="20%" headers="d0e66 "><em>phenv</em></td>
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<td align="left" valign="top" width="20%" headers="d0e68 ">Output</td>
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<td align="left" valign="top" width="40%" headers="d0e70 ">Pointer to environment handle</td>
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</tr>
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</tbody>
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</table>
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</div>
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</div>
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<div class="section"><h4 class="sectiontitle">Usage</h4> <p>There can be only one active environment
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at any one time per application. Any later call to <samp class="codeph">SQLAllocEnv()</samp> returns
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the existing environment handle.</p>
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<p>By default, the first successful call
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to <samp class="codeph">SQLFreeEnv()</samp> releases the resources associated with the
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handle. This occurs no matter how many times <samp class="codeph">SQLAllocEnv()</samp> is
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successfully called. If the environment attribute SQL_ATTR_ENVHNDL_COUNTER
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is set to SQL_TRUE, SQLFreeEnv() must be called once for each successful SQLAllocEnv()
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call before the resources associated with the handle are released. </p>
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<p>To ensure that all DB2 UDB CLI resources are kept active, the
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program that calls <samp class="codeph">SQLAllocEnv()</samp> should not stop or leave
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the stack. Otherwise, the application loses open cursors, statement handles,
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and other resources it has allocated.</p>
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</div>
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<div class="section"><h4 class="sectiontitle">Return codes</h4> <ul><li>SQL_SUCCESS</li>
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<li>SQL_ERROR</li>
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</ul>
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<p>If SQL_ERROR is returned and <em>phenv</em> is equal to SQL_NULL_HENV,
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then <samp class="codeph">SQLError()</samp> cannot be called because there is no handle
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with which to associate additional diagnostic information.</p>
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<p>If the return
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code is SQL_ERROR and the pointer to the environment handle is not equal to
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SQL_NULL_HENV, then the handle is a <em>restricted handle</em>. This means the
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handle can only be used in a call to <samp class="codeph">SQLError()</samp> to obtain
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more error information, or to <samp class="codeph">SQLFreeEnv()</samp>.</p>
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</div>
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<div class="section"><h4 class="sectiontitle">Diagnostics</h4>
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" width="100%" frame="hsides" border="1" rules="rows"><caption>Table 2. SQLAllocEnv SQLSTATEs</caption><thead align="left"><tr><th align="left" valign="bottom" width="25%" id="d0e162">SQLSTATE</th>
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<th align="left" valign="bottom" width="25%" id="d0e164">Description</th>
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<th align="left" valign="bottom" width="50%" id="d0e166">Explanation</th>
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</tr>
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</thead>
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<tbody><tr><td align="left" valign="top" width="25%" headers="d0e162 "><strong>58</strong>004</td>
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<td align="left" valign="top" width="25%" headers="d0e164 ">System error</td>
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<td align="left" valign="top" width="50%" headers="d0e166 ">Unrecoverable system error</td>
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</tr>
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</tbody>
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</table>
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</div>
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</div>
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<div class="section"><h4 class="sectiontitle">Example</h4></div>
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<div class="example" id="rzadpfnaenv__xmaenv"><a name="rzadpfnaenv__xmaenv"><!-- --></a><div class="note"><span class="notetitle">Note:</span> By using the code examples, you agree to the terms
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of the <a href="codedisclaimer.htm">Code license and disclaimer information</a>.</div>
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<div class="p"><pre>/*******************************************************
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** file = basiccon.c
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** - demonstrate basic connection to two datasources.
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** - error handling ignored for simplicity
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**
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** Functions used:
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**
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** SQLAllocConnect SQLDisconnect
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** SQLAllocEnv SQLFreeConnect
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** SQLConnect SQLFreeEnv
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**
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**
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********************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include "sqlcli.h"
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int
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connect(SQLHENV henv,
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SQLHDBC * hdbc);
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#define MAX_DSN_LENGTH 18
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#define MAX_UID_LENGTH 10
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#define MAX_PWD_LENGTH 10
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#define MAX_CONNECTIONS 5
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int
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main()
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{
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SQLHENV henv;
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SQLHDBC hdbc[MAX_CONNECTIONS];
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/* allocate an environment handle */
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SQLAllocEnv(&henv);
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/* Connect to first data source */
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connect(henv, &hdbc[0];);
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/* Connect to second data source */
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connect(henv, &hdbc[1];);
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/********* Start Processing Step *************************/
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/* allocate statement handle, execute statement, and so on */
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/********* End Processing Step ***************************/
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printf("\nDisconnecting .....\n");
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SQLFreeConnect(hdbc[0]); /* free first connection handle */
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SQLFreeConnect(hdbc[1]); /* free second connection handle */
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SQLFreeEnv(henv); /* free environment handle */
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return (SQL_SUCCESS);
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}
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/********************************************************************
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** connect - Prompt for connect options and connect **
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********************************************************************/
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int
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connect(SQLHENV henv,
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SQLHDBC * hdbc)
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{
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SQLRETURN rc;
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SQLCHAR server[MAX_DSN_LENGTH + 1], uid[MAX_UID_LENGTH + 1],
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pwd[MAX_PWD_LENGTH
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+ 1];
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SQLCHAR buffer[255];
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SQLSMALLINT outlen;
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printf("Enter Server Name:\n");
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gets((char *) server);
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printf("Enter User Name:\n");
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gets((char *) uid);
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printf("Enter Password Name:\n");
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gets((char *) pwd);
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SQLAllocConnect(henv, hdbc);/* allocate a connection handle */
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rc = SQLConnect(*hdbc, server, SQL_NTS, uid, SQL_NTS, pwd, SQL_NTS);
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if (rc != SQL_SUCCESS) {
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printf("Error while connecting to database\n");
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return (SQL_ERROR);
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} else {
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printf("Successful Connect\n");
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return (SQL_SUCCESS);
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}
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}</pre>
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</div>
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</div>
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<div class="section"><h4 class="sectiontitle">References</h4> <ul><li><a href="rzadpfnacon.htm#rzadpfnacon">SQLAllocConnect - Allocate connection handle</a></li>
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<li><a href="rzadpfnfenv.htm#rzadpfnfenv">SQLFreeEnv - Free environment handle</a></li>
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<li><a href="rzadpfnastmt.htm#rzadpfnastmt">SQLAllocStmt - Allocate a statement handle</a></li>
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</ul>
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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="rzadphdapi.htm" title="This topic provides a description of each CLI function.">DB2 UDB CLI functions</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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