CONNECT
CONNECT
CONNECT - establish a database connection
Synopsis
CONNECT TOconnection_target
[ ASconnection_name
] [ USERconnection_user
] CONNECT TO DEFAULT CONNECTconnection_user
DATABASEconnection_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[]
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
/password
user_name
IDENTIFIED BYpassword
user_name
USINGpassword
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.