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SET CONSTRAINT[S]

Purpose

Use the SET CONSTRAINTS statement to specify, for a particular transaction, whether a deferrable constraint is checked following each DML statement or when the transaction is committed.

Prerequisites

To specify when a deferrable constraint is checked, you must have SELECT privilege on the table to which the constraint is applied unless the table is in your schema.

Syntax

set_constraints::=

Description of the illustration set_constraints.gif

Semantics

constraint

Specify the name of one or more integrity constraints.

ALL

Specify ALL to set all deferrable constraints for this transaction.

IMMEDIATE

Specify IMMEDIATE to indicate that the conditions specified by the deferrable constraint are checked immediately after each DML statement.

DEFERRED

Specify DEFERRED to indicate that the conditions specified by the deferrable constraint are checked when the transaction is committed.

Note: You can verify the success of deferrable constraints prior to committing them by issuing a SET CONSTRAINTS ALL IMMEDIATE statement.

Examples

Setting Constraints: Examples

The following statement sets all deferrable constraints in this transaction to be checked immediately following each DML statement:

SET CONSTRAINTS ALL IMMEDIATE;

The following statement checks three deferred constraints when the transaction is committed. This example fails if the constraints were specified to be NOT DEFERRABLE.

SET CONSTRAINTS emp_job_nn, emp_salary_min ,
   hr.jhist_dept_fk@remote DEFERRED;