NAME¶

CREATE CONSTRAINT TRIGGER - define a new constraint trigger

SYNOPSIS¶

CREATE CONSTRAINT TRIGGER name


    AFTER event [ OR ... ]


    ON table_name


    [ FROM referenced_table_name ]


    { NOT DEFERRABLE | [ DEFERRABLE ] { INITIALLY IMMEDIATE | INITIALLY DEFERRED } }


    FOR EACH ROW


    EXECUTE PROCEDURE funcname ( arguments )

DESCRIPTION¶

CREATE CONSTRAINT TRIGGER creates a constraint trigger. This is the same as a regular trigger except that the timing of the trigger firing can be adjusted using SET CONSTRAINTS [set_constraints(7)]. Constraint triggers must be AFTER ROW triggers. They can be fired either at the end of the statement causing the triggering event, or at the end of the containing transaction; in the latter case they are said to be deferred. A pending deferred-trigger firing can also be forced to happen immediately by using SET CONSTRAINTS.

PARAMETERS¶

name

The name of the constraint trigger. This is also the name to use when modifying the trigger's behavior using SET CONSTRAINTS. The name cannot be schema-qualified — the trigger inherits the schema of its table.

event

One of INSERT, UPDATE, or DELETE; this specifies the event that will fire the trigger. Multiple events can be specified using OR.

table_name

The (possibly schema-qualified) name of the table in which the triggering events occur.

referenced_table_name

The (possibly schema-qualified) name of another table referenced by the constraint. This option is used for foreign-key constraints and is not recommended for general use.

DEFERRABLE

NOT DEFERRABLE

INITIALLY IMMEDIATE

INITIALLY DEFERRED

The default timing of the trigger. See the CREATE TABLE [create_table(7)] documentation for details of these constraint options.

funcname

The function to call when the trigger is fired. See CREATE TRIGGER [create_trigger(7)] for details.

arguments

Optional argument strings to pass to the trigger function. See CREATE TRIGGER [create_trigger(7)] for details.

COMPATIBILITY¶

CREATE CONSTRAINT TRIGGER is a PostgreSQL extension of the SQL standard.

SEE ALSO¶

CREATE TRIGGER [create_trigger(7)], DROP TRIGGER [drop_trigger(7)], SET CONSTRAINTS [set_constraints(7)]