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Green_GoodERP18_FSJ_Standard/PostgreSQL/doc/postgresql/html/ecpg-sql-connect.html

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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 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><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 12.4 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">

  3. 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> ]

  4. CONNECT TO DEFAULT

  5. CONNECT <em class="replaceable"><code>connection_user</code></em>

  6. DATABASE <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 connection

  9.      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><span class="term"><em class="replaceable"><code>connection_target</code></em></span></dt><dd><p>

  11.         <em class="replaceable"><code>connection_target</code></em>

  12.         specifies the target server of the connection on one of

  13.         several forms.

  14. 

  15.         </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>

  16.             Connect over TCP/IP

  17.            </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>

  18.             Connect over Unix-domain sockets

  19.            </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>

  20.             Connect over TCP/IP

  21.            </p></dd><dt><span class="term">SQL string constant</span></dt><dd><p>

  22.             containing a value in one of the above forms

  23.            </p></dd><dt><span class="term">host variable</span></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 the

  26.             above forms

  27.            </p></dd></dl></div><p>

  28.        </p></dd><dt><span class="term"><em class="replaceable"><code>connection_name</code></em></span></dt><dd><p>

  29.         An optional identifier for the connection, so that it can be

  30.         referred to in other commands.  This can be an SQL identifier

  31.         or a host variable.

  32.        </p></dd><dt><span class="term"><em class="replaceable"><code>connection_user</code></em></span></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 forms

  36.         <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>, or

  38.         <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, string

  41.         constants, or host variables.

  42.        </p></dd><dt><span class="term"><code class="literal">DEFAULT</code></span></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">

  47. EXEC SQL CONNECT TO "connectdb" AS main;

  48. EXEC SQL CONNECT TO "connectdb" AS second;

  49. EXEC SQL CONNECT TO "unix:postgresql://200.46.204.71/connectdb" AS main USER connectuser;

  50. EXEC SQL CONNECT TO "unix:postgresql://localhost/connectdb" AS main USER connectuser;

  51. EXEC SQL CONNECT TO 'connectdb' AS main;

  52. EXEC SQL CONNECT TO 'unix:postgresql://localhost/connectdb' AS main USER :user;

  53. EXEC SQL CONNECT TO :db AS :id;

  54. EXEC SQL CONNECT TO :db USER connectuser USING :pw;

  55. EXEC SQL CONNECT TO @localhost AS main USER connectdb;

  56. EXEC SQL CONNECT TO REGRESSDB1 as main;

  57. EXEC SQL CONNECT TO AS main USER connectdb;

  58. EXEC SQL CONNECT TO connectdb AS :id;

  59. EXEC SQL CONNECT TO connectdb AS main USER connectuser/connectdb;

  60. EXEC SQL CONNECT TO connectdb AS main;

  61. EXEC SQL CONNECT TO connectdb@localhost AS main;

  62. EXEC SQL CONNECT TO tcp:postgresql://localhost/ USER connectdb;

  63. EXEC SQL CONNECT TO tcp:postgresql://localhost/connectdb USER connectuser IDENTIFIED BY connectpw;

  64. EXEC SQL CONNECT TO tcp:postgresql://localhost:20/connectdb USER connectuser IDENTIFIED BY connectpw;

  65. EXEC SQL CONNECT TO unix:postgresql://localhost/ AS main USER connectdb;

  66. EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb AS main USER connectuser;

  67. EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb USER connectuser IDENTIFIED BY "connectpw";

  68. EXEC SQL CONNECT TO unix:postgresql://localhost/connectdb USER connectuser USING "connectpw";

  69. EXEC 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 host

  73.      variables to specify connection parameters:

  74. </p><pre class="programlisting">

  75. int

  76. main(void)

  77. {

  78. EXEC 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 */

  84. EXEC 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, but

  107.      the format of the connection parameters is

  108.      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">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ecpg-sql-commands.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ecpg-sql-deallocate-descriptor.html">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">Home</a></td><td width="40%" align="right" valign="top"> DEALLOCATE DESCRIPTOR</td></tr></table></div></body></html>
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