CONNECT
CONNECT — establish a database connection
Synopsis
CONNECT TOconnection_target[ ASconnection_name] [ USERconnection_user]CONNECT TO DEFAULTCONNECTconnection_userDATABASEconnection_target
Description
TheCONNECT command establishes a connection between the client and the PostgreSQL server.
Parameters
connection_target#connection_targetspecifies 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[]orVARCHAR[]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/passworduser_nameIDENTIFIED BYpassworduser_nameUSINGpasswordUser 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:
intmain(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.