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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>CONNECT</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets V1.79.1" /><link rel="prev" href="ecpg-sql-allocate-descriptor.html" title="ALLOCATE DESCRIPTOR" /><link rel="next" href="ecpg-sql-deallocate-descriptor.html" title="DEALLOCATE DESCRIPTOR" /></head><body id="docContent" class="container-fluid col-10"><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">CONNECT</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="ecpg-sql-allocate-descriptor.html" title="ALLOCATE DESCRIPTOR">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="ecpg-sql-commands.html" title="35.14. Embedded SQL Commands">Up</a></td><th width="60%" align="center">35.14. Embedded SQL Commands</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 13.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="ecpg-sql-deallocate-descriptor.html" title="DEALLOCATE DESCRIPTOR">Next</a></td></tr></table><hr></hr></div><div class="refentry" id="ECPG-SQL-CONNECT"><div class="titlepage"></div><div class="refnamediv"><h2>CONNECT</h2><p>CONNECT — establish a database connection</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">
CONNECT TO <em class="replaceable"><code>connection_target</code></em> [ AS <em class="replaceable"><code>connection_name</code></em> ] [ USER <em class="replaceable"><code>connection_user</code></em> ]
CONNECT TO DEFAULT
CONNECT <em class="replaceable"><code>connection_user</code></em>
DATABASE <em class="replaceable"><code>connection_target</code></em>
</pre></div><div class="refsect1" id="id-1.7.5.20.4.3"><h2>Description</h2><p>
The <code class="command">CONNECT</code> command establishes a connection
between the client and the PostgreSQL server.
</p></div><div class="refsect1" id="id-1.7.5.20.4.4"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>connection_target</code></em></span></dt><dd><p>
<em class="replaceable"><code>connection_target</code></em>
specifies the target server of the connection on one of
several forms.
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term">[ <em class="replaceable"><code>database_name</code></em> ] [ <code class="literal">@</code><em class="replaceable"><code>host</code></em> ] [ <code class="literal">:</code><em class="replaceable"><code>port</code></em> ]</span></dt><dd><p>
Connect over TCP/IP
</p></dd><dt><span class="term"><code class="literal">unix:postgresql://</code><em class="replaceable"><code>host</code></em> [ <code class="literal">:</code><em class="replaceable"><code>port</code></em> ] <code class="literal">/</code> [ <em class="replaceable"><code>database_name</code></em> ] [ <code class="literal">?</code><em class="replaceable"><code>connection_option</code></em> ]</span></dt><dd><p>
Connect over Unix-domain sockets
</p></dd><dt><span class="term"><code class="literal">tcp:postgresql://</code><em class="replaceable"><code>host</code></em> [ <code class="literal">:</code><em class="replaceable"><code>port</code></em> ] <code class="literal">/</code> [ <em class="replaceable"><code>database_name</code></em> ] [ <code class="literal">?</code><em class="replaceable"><code>connection_option</code></em> ]</span></dt><dd><p>
Connect over TCP/IP
</p></dd><dt><span class="term">SQL string constant</span></dt><dd><p>
containing a value in one of the above forms
</p></dd><dt><span class="term">host variable</span></dt><dd><p>
host variable of type <code class="type">char[]</code>
or <code class="type">VARCHAR[]</code> containing a value in one of the
above forms
</p></dd></dl></div><p>
</p></dd><dt><span class="term"><em class="replaceable"><code>connection_name</code></em></span></dt><dd><p>
An optional identifier for the connection, so that it can be
referred to in other commands. This can be an SQL identifier
or a host variable.
</p></dd><dt><span class="term"><em class="replaceable"><code>connection_user</code></em></span></dt><dd><p>
The user name for the database connection.
</p><p>
This parameter can also specify user name and password, using one the forms
<code class="literal"><em class="replaceable"><code>user_name</code></em>/<em class="replaceable"><code>password</code></em></code>,
<code class="literal"><em class="replaceable"><code>user_name</code></em> IDENTIFIED BY <em class="replaceable"><code>password</code></em></code>, or
<code class="literal"><em class="replaceable"><code>user_name</code></em> USING <em class="replaceable"><code>password</code></em></code>.
</p><p>
User name and password can be SQL identifiers, string
constants, or host variables.
</p></dd><dt><span class="term"><code class="literal">DEFAULT</code></span></dt><dd><p>
Use all default connection parameters, as defined by libpq.
</p></dd></dl></div></div><div class="refsect1" id="id-1.7.5.20.4.5"><h2>Examples</h2><p>
Here a several variants for specifying connection parameters:
</p><pre class="programlisting">
EXEC SQL CONNECT TO "connectdb" AS main;
EXEC SQL CONNECT TO "connectdb" AS second;
EXEC SQL CONNECT TO "unix:postgresql://200.46.204.71/connectdb" AS main USER connectuser;
EXEC SQL CONNECT TO "unix:postgresql://localhost/connectdb" AS main USER connectuser;
EXEC SQL CONNECT TO 'connectdb' AS main;
EXEC SQL CONNECT TO 'unix:postgresql://localhost/connectdb' AS main USER :user;
EXEC SQL CONNECT TO :db AS :id;
EXEC SQL CONNECT TO :db USER connectuser USING :pw;
EXEC SQL CONNECT TO @localhost AS main USER connectdb;
EXEC SQL CONNECT TO REGRESSDB1 as main;
EXEC SQL CONNECT TO AS main USER connectdb;
EXEC SQL CONNECT TO connectdb AS :id;
EXEC SQL CONNECT TO connectdb AS main USER connectuser/connectdb;
EXEC SQL CONNECT TO connectdb AS main;
EXEC SQL CONNECT TO connectdb@localhost AS main;
EXEC SQL CONNECT TO tcp:postgresql://localhost/ USER connectdb;
EXEC SQL CONNECT TO tcp:postgresql://localhost/connectdb USER connectuser IDENTIFIED BY connectpw;
EXEC SQL CONNECT TO tcp:postgresql://localhost:20/connectdb USER connectuser IDENTIFIED BY connectpw;
EXEC SQL CONNECT TO unix:postgresql://localhost/ AS main USER connectdb;
EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb AS main USER connectuser;
EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb USER connectuser IDENTIFIED BY "connectpw";
EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb USER connectuser USING "connectpw";
EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb?connect_timeout=14 USER connectuser;
</pre><p>
</p><p>
Here is an example program that illustrates the use of host
variables to specify connection parameters:
</p><pre class="programlisting">
int
main(void)
{
EXEC SQL BEGIN DECLARE SECTION;
char *dbname = "testdb"; /* database name */
char *user = "testuser"; /* connection user name */
char *connection = "tcp:postgresql://localhost:5432/testdb";
/* connection string */
char ver[256]; /* buffer to store the version string */
EXEC SQL END DECLARE SECTION;
ECPGdebug(1, stderr);
EXEC SQL CONNECT TO :dbname USER :user;
EXEC SQL SELECT pg_catalog.set_config('search_path', '', false); EXEC SQL COMMIT;
EXEC SQL SELECT version() INTO :ver;
EXEC SQL DISCONNECT;
printf("version: %s\n", ver);
EXEC SQL CONNECT TO :connection USER :user;
EXEC SQL SELECT pg_catalog.set_config('search_path', '', false); EXEC SQL COMMIT;
EXEC SQL SELECT version() INTO :ver;
EXEC SQL DISCONNECT;
printf("version: %s\n", ver);
return 0;
}
</pre><p>
</p></div><div class="refsect1" id="id-1.7.5.20.4.6"><h2>Compatibility</h2><p>
<code class="command">CONNECT</code> is specified in the SQL standard, but
the format of the connection parameters is
implementation-specific.
</p></div><div class="refsect1" id="id-1.7.5.20.4.7"><h2>See Also</h2><span class="simplelist"><a class="xref" href="ecpg-sql-disconnect.html" title="DISCONNECT">DISCONNECT</a>, <a class="xref" href="ecpg-sql-set-connection.html" title="SET CONNECTION">SET CONNECTION</a></span></div></div><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navfooter"><hr></hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ecpg-sql-allocate-descriptor.html" title="ALLOCATE DESCRIPTOR">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ecpg-sql-commands.html" title="35.14. Embedded SQL Commands">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ecpg-sql-deallocate-descriptor.html" title="DEALLOCATE DESCRIPTOR">Next</a></td></tr><tr><td width="40%" align="left" valign="top">ALLOCATE DESCRIPTOR </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 13.4 Documentation">Home</a></td><td width="40%" align="right" valign="top"> DEALLOCATE DESCRIPTOR</td></tr></table></div></body></html>
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