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<title>SQLAllocEnv - Allocate environment handle</title>
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<h1 class="topictitle1">SQLAllocEnv - Allocate environment handle</h1>
<div><div class="section"><h4 class="sectiontitle">Purpose</h4> <p><samp class="codeph">SQLAllocEnv()</samp> allocates
an environment handle and associated resources.</p>
<p>An application must
call this function before <samp class="codeph">SQLAllocConnect()</samp> or any other DB2<sup>®</sup> UDB
CLI functions. The <em>henv</em> value is passed in all later function calls
that require an environment handle as input.</p>
</div>
<div class="section"><h4 class="sectiontitle">Syntax</h4> <pre>SQLRETURN SQLAllocEnv (SQLHENV *phenv);</pre>
</div>
<div class="section"><h4 class="sectiontitle">Function arguments</h4>
<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>
<th align="left" valign="bottom" width="20%" id="d0e66">Argument</th>
<th align="left" valign="bottom" width="20%" id="d0e68">Use</th>
<th align="left" valign="bottom" width="40%" id="d0e70">Description</th>
</tr>
</thead>
<tbody><tr><td align="left" valign="top" width="20%" headers="d0e64 ">SQLHENV *</td>
<td align="left" valign="top" width="20%" headers="d0e66 "><em>phenv</em></td>
<td align="left" valign="top" width="20%" headers="d0e68 ">Output</td>
<td align="left" valign="top" width="40%" headers="d0e70 ">Pointer to environment handle</td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="section"><h4 class="sectiontitle">Usage</h4> <p>There can be only one active environment
at any one time per application. Any later call to <samp class="codeph">SQLAllocEnv()</samp> returns
the existing environment handle.</p>
<p>By default, the first successful call
to <samp class="codeph">SQLFreeEnv()</samp> releases the resources associated with the
handle. This occurs no matter how many times <samp class="codeph">SQLAllocEnv()</samp> is
successfully called. If the environment attribute SQL_ATTR_ENVHNDL_COUNTER
is set to SQL_TRUE, SQLFreeEnv() must be called once for each successful SQLAllocEnv()
call before the resources associated with the handle are released. </p>
<p>To ensure that all DB2 UDB CLI resources are kept active, the
program that calls <samp class="codeph">SQLAllocEnv()</samp> should not stop or leave
the stack. Otherwise, the application loses open cursors, statement handles,
and other resources it has allocated.</p>
</div>
<div class="section"><h4 class="sectiontitle">Return codes</h4> <ul><li>SQL_SUCCESS</li>
<li>SQL_ERROR</li>
</ul>
<p>If SQL_ERROR is returned and <em>phenv</em> is equal to SQL_NULL_HENV,
then <samp class="codeph">SQLError()</samp> cannot be called because there is no handle
with which to associate additional diagnostic information.</p>
<p>If the return
code is SQL_ERROR and the pointer to the environment handle is not equal to
SQL_NULL_HENV, then the handle is a <em>restricted handle</em>. This means the
handle can only be used in a call to <samp class="codeph">SQLError()</samp> to obtain
more error information, or to <samp class="codeph">SQLFreeEnv()</samp>.</p>
</div>
<div class="section"><h4 class="sectiontitle">Diagnostics</h4>
<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>
<th align="left" valign="bottom" width="25%" id="d0e164">Description</th>
<th align="left" valign="bottom" width="50%" id="d0e166">Explanation</th>
</tr>
</thead>
<tbody><tr><td align="left" valign="top" width="25%" headers="d0e162 "><strong>58</strong>004</td>
<td align="left" valign="top" width="25%" headers="d0e164 ">System error</td>
<td align="left" valign="top" width="50%" headers="d0e166 ">Unrecoverable system error</td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="section"><h4 class="sectiontitle">Example</h4></div>
<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
of the <a href="codedisclaimer.htm">Code license and disclaimer information</a>.</div>
<div class="p"><pre>/*******************************************************
** file = basiccon.c
** - demonstrate basic connection to two datasources.
** - error handling ignored for simplicity
**
** Functions used:
**
** SQLAllocConnect SQLDisconnect
** SQLAllocEnv SQLFreeConnect
** SQLConnect SQLFreeEnv
**
**
********************************************************/
#include &lt;stdio.h&gt;
#include &lt;stdlib.h&gt;
#include "sqlcli.h"
int
connect(SQLHENV henv,
SQLHDBC * hdbc);
#define MAX_DSN_LENGTH 18
#define MAX_UID_LENGTH 10
#define MAX_PWD_LENGTH 10
#define MAX_CONNECTIONS 5
int
main()
{
SQLHENV henv;
SQLHDBC hdbc[MAX_CONNECTIONS];
/* allocate an environment handle */
SQLAllocEnv(&amp;henv);
/* Connect to first data source */
connect(henv, &amp;hdbc[0];);
/* Connect to second data source */
connect(henv, &amp;hdbc[1];);
/********* Start Processing Step *************************/
/* allocate statement handle, execute statement, and so on */
/********* End Processing Step ***************************/
printf("\nDisconnecting .....\n");
SQLFreeConnect(hdbc[0]); /* free first connection handle */
SQLFreeConnect(hdbc[1]); /* free second connection handle */
SQLFreeEnv(henv); /* free environment handle */
return (SQL_SUCCESS);
}
/********************************************************************
** connect - Prompt for connect options and connect **
********************************************************************/
int
connect(SQLHENV henv,
SQLHDBC * hdbc)
{
SQLRETURN rc;
SQLCHAR server[MAX_DSN_LENGTH + 1], uid[MAX_UID_LENGTH + 1],
pwd[MAX_PWD_LENGTH
+ 1];
SQLCHAR buffer[255];
SQLSMALLINT outlen;
printf("Enter Server Name:\n");
gets((char *) server);
printf("Enter User Name:\n");
gets((char *) uid);
printf("Enter Password Name:\n");
gets((char *) pwd);
SQLAllocConnect(henv, hdbc);/* allocate a connection handle */
rc = SQLConnect(*hdbc, server, SQL_NTS, uid, SQL_NTS, pwd, SQL_NTS);
if (rc != SQL_SUCCESS) {
printf("Error while connecting to database\n");
return (SQL_ERROR);
} else {
printf("Successful Connect\n");
return (SQL_SUCCESS);
}
}</pre>
</div>
</div>
<div class="section"><h4 class="sectiontitle">References</h4> <ul><li><a href="rzadpfnacon.htm#rzadpfnacon">SQLAllocConnect - Allocate connection handle</a></li>
<li><a href="rzadpfnfenv.htm#rzadpfnfenv">SQLFreeEnv - Free environment handle</a></li>
<li><a href="rzadpfnastmt.htm#rzadpfnastmt">SQLAllocStmt - Allocate a statement handle</a></li>
</ul>
</div>
</div>
<div>
<div class="familylinks">
<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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