Firebird 2.1 Language Reference Update

DDL statements
Description: Creates a trigger, a block of PSQL code that is executed automatically upon certain database events
or mutations to a table or view.
Syntax:
CREATE TRIGGER name
{
|
| }
AS
[]
BEGIN
[]
END
::= FOR {tablename | viewname}
[ACTIVE | INACTIVE]
{BEFORE | AFTER}
[POSITION number]
::= [ACTIVE | INACTIVE]
{BEFORE | AFTER}
[POSITION number]
ON {tablename | viewname}
::= [ACTIVE | INACTIVE]
ON db_event
[POSITION number]
::= mutation [OR mutation [OR mutation]]
mutation ::= INSERT | UPDATE | DELETE
db_event ::= CONNECT | DISCONNECT | TRANSACTION START
| TRANSACTION COMMIT | TRANSACTION ROLLBACK
number ::= 0..32767 (default is 0)
::= See PSQL::DECLARE for the exact syntax
• “Legacy” and “sql2003” relation triggers are exactly the same. The only thing that differs is the
creation syntax.
• Triggers with lower position numbers fire first. Position numbers need not be unique, but if two
or more triggers have the same position, the firing order between them is undefined.
• When defining relation triggers, each mutation type (INSERT, UPDATE or DELETE) may occur
at most once in the mutation list.
SQL-2003-compliant syntax for relation triggers
Added in: 2.1
Description: Since Firebird 2.1, an alternative, SQL-2003-compliant syntax can be used for triggers on tables
and views. Instead of specifying “FOR relationname” before the event type and the optional directives surrounding
it, you can now put “ON relationname” after it, as shown in the syntax earlier in this chapter.
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