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1<?xml version="1.0" encoding="UTF-8" standalone="no"?>2<!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 Vsnapshot" /><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 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="36.14. Embedded SQL Commands">Up</a></td><th width="60%" align="center">36.14. Embedded SQL Commands</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 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 /></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">3CONNECT 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> ]4CONNECT TO DEFAULT5CONNECT <em class="replaceable"><code>connection_user</code></em>6DATABASE <em class="replaceable"><code>connection_target</code></em>7</pre></div><div class="refsect1" id="id-1.7.5.20.4.3"><h2>Description</h2><p>8     The <code class="command">CONNECT</code> command establishes a connection9     between the client and the PostgreSQL server.10    </p></div><div class="refsect1" id="id-1.7.5.20.4.4"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt id="ECPG-SQL-CONNECT-CONNECTION-TARGET"><span class="term"><em class="replaceable"><code>connection_target</code></em></span> <a href="#ECPG-SQL-CONNECT-CONNECTION-TARGET" class="id_link">#</a></dt><dd><p>11        <em class="replaceable"><code>connection_target</code></em>12        specifies the target server of the connection on one of13        several forms.14 15        </p><div class="variablelist"><dl class="variablelist"><dt id="ECPG-SQL-CONNECT-CONNECTION-TARGET-DATABASE-NAME"><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> <a href="#ECPG-SQL-CONNECT-CONNECTION-TARGET-DATABASE-NAME" class="id_link">#</a></dt><dd><p>16            Connect over TCP/IP17           </p></dd><dt id="ECPG-SQL-CONNECT-CONNECTION-TARGET-UNIX-DOMAIN-SOCKETS"><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> <a href="#ECPG-SQL-CONNECT-CONNECTION-TARGET-UNIX-DOMAIN-SOCKETS" class="id_link">#</a></dt><dd><p>18            Connect over Unix-domain sockets19           </p></dd><dt id="ECPG-SQL-CONNECT-CONNECTION-TARGET-TCP-IP"><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> <a href="#ECPG-SQL-CONNECT-CONNECTION-TARGET-TCP-IP" class="id_link">#</a></dt><dd><p>20            Connect over TCP/IP21           </p></dd><dt id="ECPG-SQL-CONNECT-CONNECTION-TARGET-CONSTANT"><span class="term">SQL string constant</span> <a href="#ECPG-SQL-CONNECT-CONNECTION-TARGET-CONSTANT" class="id_link">#</a></dt><dd><p>22            containing a value in one of the above forms23           </p></dd><dt id="ECPG-SQL-CONNECT-CONNECTION-TARGET-HOST-VARIABLE"><span class="term">host variable</span> <a href="#ECPG-SQL-CONNECT-CONNECTION-TARGET-HOST-VARIABLE" class="id_link">#</a></dt><dd><p>24            host variable of type <code class="type">char[]</code>25            or <code class="type">VARCHAR[]</code> containing a value in one of the26            above forms27           </p></dd></dl></div><p>28       </p></dd><dt id="ECPG-SQL-CONNECT-CONNECTION-NAME"><span class="term"><em class="replaceable"><code>connection_name</code></em></span> <a href="#ECPG-SQL-CONNECT-CONNECTION-NAME" class="id_link">#</a></dt><dd><p>29        An optional identifier for the connection, so that it can be30        referred to in other commands.  This can be an SQL identifier31        or a host variable.32       </p></dd><dt id="ECPG-SQL-CONNECT-CONNECTION-USER"><span class="term"><em class="replaceable"><code>connection_user</code></em></span> <a href="#ECPG-SQL-CONNECT-CONNECTION-USER" class="id_link">#</a></dt><dd><p>33        The user name for the database connection.34       </p><p>35        This parameter can also specify user name and password, using one the forms36        <code class="literal"><em class="replaceable"><code>user_name</code></em>/<em class="replaceable"><code>password</code></em></code>,37        <code class="literal"><em class="replaceable"><code>user_name</code></em> IDENTIFIED BY <em class="replaceable"><code>password</code></em></code>, or38        <code class="literal"><em class="replaceable"><code>user_name</code></em> USING <em class="replaceable"><code>password</code></em></code>.39       </p><p>40        User name and password can be SQL identifiers, string41        constants, or host variables.42       </p></dd><dt id="ECPG-SQL-CONNECT-DEFAULT"><span class="term"><code class="literal">DEFAULT</code></span> <a href="#ECPG-SQL-CONNECT-DEFAULT" class="id_link">#</a></dt><dd><p>43        Use all default connection parameters, as defined by libpq.44       </p></dd></dl></div></div><div class="refsect1" id="id-1.7.5.20.4.5"><h2>Examples</h2><p>45     Here a several variants for specifying connection parameters:46</p><pre class="programlisting">47EXEC SQL CONNECT TO "connectdb" AS main;48EXEC SQL CONNECT TO "connectdb" AS second;49EXEC SQL CONNECT TO "unix:postgresql://200.46.204.71/connectdb" AS main USER connectuser;50EXEC SQL CONNECT TO "unix:postgresql://localhost/connectdb" AS main USER connectuser;51EXEC SQL CONNECT TO 'connectdb' AS main;52EXEC SQL CONNECT TO 'unix:postgresql://localhost/connectdb' AS main USER :user;53EXEC SQL CONNECT TO :db AS :id;54EXEC SQL CONNECT TO :db USER connectuser USING :pw;55EXEC SQL CONNECT TO @localhost AS main USER connectdb;56EXEC SQL CONNECT TO REGRESSDB1 as main;57EXEC SQL CONNECT TO AS main USER connectdb;58EXEC SQL CONNECT TO connectdb AS :id;59EXEC SQL CONNECT TO connectdb AS main USER connectuser/connectdb;60EXEC SQL CONNECT TO connectdb AS main;61EXEC SQL CONNECT TO connectdb@localhost AS main;62EXEC SQL CONNECT TO tcp:postgresql://localhost/ USER connectdb;63EXEC SQL CONNECT TO tcp:postgresql://localhost/connectdb USER connectuser IDENTIFIED BY connectpw;64EXEC SQL CONNECT TO tcp:postgresql://localhost:20/connectdb USER connectuser IDENTIFIED BY connectpw;65EXEC SQL CONNECT TO unix:postgresql://localhost/ AS main USER connectdb;66EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb AS main USER connectuser;67EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb USER connectuser IDENTIFIED BY "connectpw";68EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb USER connectuser USING "connectpw";69EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb?connect_timeout=14 USER connectuser;70</pre><p>71    </p><p>72     Here is an example program that illustrates the use of host73     variables to specify connection parameters:74</p><pre class="programlisting">75int76main(void)77{78EXEC SQL BEGIN DECLARE SECTION;79    char *dbname     = "testdb";    /* database name */80    char *user       = "testuser";  /* connection user name */81    char *connection = "tcp:postgresql://localhost:5432/testdb";82                                    /* connection string */83    char ver[256];                  /* buffer to store the version string */84EXEC SQL END DECLARE SECTION;85 86    ECPGdebug(1, stderr);87 88    EXEC SQL CONNECT TO :dbname USER :user;89    EXEC SQL SELECT pg_catalog.set_config('search_path', '', false); EXEC SQL COMMIT;90    EXEC SQL SELECT version() INTO :ver;91    EXEC SQL DISCONNECT;92 93    printf("version: %s\n", ver);94 95    EXEC SQL CONNECT TO :connection USER :user;96    EXEC SQL SELECT pg_catalog.set_config('search_path', '', false); EXEC SQL COMMIT;97    EXEC SQL SELECT version() INTO :ver;98    EXEC SQL DISCONNECT;99 100    printf("version: %s\n", ver);101 102    return 0;103}104</pre><p>105    </p></div><div class="refsect1" id="id-1.7.5.20.4.6"><h2>Compatibility</h2><p>106     <code class="command">CONNECT</code> is specified in the SQL standard, but107     the format of the connection parameters is108     implementation-specific.109    </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 class="navfooter"><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="36.14. 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 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> DEALLOCATE DESCRIPTOR</td></tr></table></div></body></html>