CONNECT

CONNECT
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CONNECT — establish a database connection

Synopsis

+CONNECT TO connection_target [ AS connection_name ] [ USER connection_user ]
+CONNECT TO DEFAULT
+CONNECT connection_user
+DATABASE connection_target
+

Description

+ The CONNECT command establishes a connection + between the client and the PostgreSQL server. +

Parameters

connection_target

+ connection_target + specifies the target server of the connection on one of + several forms. + +

[ database_name ] [ @host ] [ :port ]: + Connect over TCP/IP +
unix:postgresql://host [ :port ] / [ database_name ] [ ?connection_option ]: + Connect over Unix-domain sockets +
tcp:postgresql://host [ :port ] / [ database_name ] [ ?connection_option ]: + Connect over TCP/IP +
SQL string constant: + containing a value in one of the above forms +
host variable: + host variable of type char[] + or VARCHAR[] containing a value in one of the + above forms +

connection_name

+ 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. +

connection_user

+ The user name for the database connection. +

+ This parameter can also specify user name and password, using one the forms + user_name/password, + user_name IDENTIFIED BY password, or + user_name USING password. +

+ User name and password can be SQL identifiers, string + constants, or host variables. +

DEFAULT

+ Use all default connection parameters, as defined by libpq. +

Examples

+ Here a several variants for specifying connection parameters: +

+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;
+

+ Here is an example program that illustrates the use of host + variables to specify connection parameters: +

+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;
+}
+

Compatibility

+ CONNECT is specified in the SQL standard, but + the format of the connection parameters is + implementation-specific. +

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