CREATE CONSTRAINT TRIGGEPostgreSQL 9.0.23 DocumentCREATE CONSTRAINT TRIGGER(7)NAMECREATE_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
[ WHEN ( condition ) ]
EXECUTE PROCEDURE function_name ( 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.
condition
A Boolean expression that determines whether the trigger function
will actually be executed. This acts the same as in CREATE TRIGGER
(CREATE_TRIGGER(7)). Note in particular that evaluation of the WHEN
condition is not deferred, but occurs immediately after the row
update operation is performed. If the condition does not evaluate
to true then the trigger is not queued for deferred execution.
function_name
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))
PostgreSQL 9.0.23 2015-10-05 CREATE CONSTRAINT TRIGGER(7)
