CONNECT TO

Opens a new database session in multi-session mode.

Syntax

CONNECT TO { dbname | DEFAULT } [ AS session ]
    [ USER login USING auth [ TRUSTED ] ]
    [ WITH CONCURRENT TRANSACTION ]
  1. dbname is the database specification.
  2. session identifies the database session. By default, it is dbname.
  3. login is the name of the database user.
  4. auth is the password to authenticate the database user, or an external authentication token.

Usage

The CONNECT TO instruction opens a database connection. If the instruction successfully connects to the database environment, the connection becomes the current database session for the program.

Note:

The DEFAULT clause of CONNECT TO is specific to IBM® Informix®.

The session name is case-sensitive.

A program can connect to several database environments at the same time (using different database drivers), and it can establish multiple connections to the same database environment, provided each connection has a unique connection name.

The connection is closed with the DISCONNECT instruction, or when the program ends.

When the USER login USING auth clause is specified, the database user is identified by login and auth, ignoring all other user settings defined in FGLPROFILE or as connection string parameters.

The auth parameter can be a simple password for internal database users, but for some types of database engines, it can be used to specify an external authentication token, such as a distinguished name (DN). For more details, see the SQL adaptation guide for your database type.

When the CONNECT TO instruction does not specify the USER/USING clause, the database user is typically authenticated through the operating system user. If needed, the database user name and password can be provided from a callback function, with the dbi.default.userauth.callback FGLPROFILE entry.

The TRUSTED keyword can be used after the USER/USING clause, to indicate that the specified user is trusted by an IBM Informix trusted context. When a trusted connection is established, a program can use the SET SESSION AUTHORIZATION instruction, to switch between database users associated to the connection user, as defined by the related trusted context. See Informix database server documentation for more details.

Note:

The TRUSTED clause of CONNECT TO is specific to IBM Informix.

The CONNECT TO instruction raises an exception if the connection can not be established, for example, if you specify a database that the runtime system cannot locate, or cannot open, or for which the user of your program does not have access privileges.

The WITH CONCURRENT TRANSACTION clause allows a program to open several transactions concurrently in different database sessions: The transaction can be started with the BEGIN WORK statement in a given connection context, then the program can switch to another connection with SET CONNECTION, and when done, switch back to the first connection to issue a COMMIT WORK or ROLLBACK WORK. This is supported for IBM Informix database servers.
Note:

The WITH CONCURRENT TRANSACTION option is ignored with non-Informix database server types, but it can be used in the CONNECT TO statement, for consistency with Informix.

A CONNECT TO statement cannot be executed with dynamic SQL (PREPARE + EXECUTE).

With IBM Informix database servers, when using the CONNECT TO DEFAULT, you connect to the default IBM Informix database server, identified by the INFORMIXSERVER environment variable, without any database selection.

When using IBM Informix on UNIX™, the only restriction on establishing multiple connections to the same database environment is that an program can establish only one connection to each local server that uses the shared-memory connection mechanism. To find out whether a local server uses the shared-memory connection mechanism or the local-loopback connection mechanism, examine the $INFORMIXDIR/etc/sqlhosts file.

Example

MAIN
  DEFINE uname, upswd VARCHAR(50) 
  CONNECT TO "stores1" -- Session name is "stores1"
  CONNECT TO "stores1" AS "SA" -- Session name is "SA"
  CALL login_dialog() RETURNING uname, upswd
  CONNECT TO "stores2" AS "SB" USER uname USING upswd
END MAIN