Declaring Multiple Databases

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A SQL program, but not a DSQL program, can access multiple databases at the same time. In multi-database programs, database handles are required. A handle is used to:

• Reference individual databases in a multi-database transaction.
• Qualify table names.
• Specify databases to open in CONNECT statements.
• Indicate databases to close with DISCONNECT, COMMIT RELEASE, and ROLLBACK RELEASE.

DSQL programs can access only a single database at a time, so database handle use is restricted to connecting to and disconnecting from a database.

In multi-database programs, each database must be declared in a separate SET DATABASE statement. For example, the following code contains two SET DATABASE statements:

. . .
EXEC SQL
SET DATABASE DB2 = 'employee2.ib';
EXEC SQL
SET DATABASE DB1 = 'employee.ib';
. . .

Topics

• Using Handles for Table Names
• Using Handles with Operations