2.3.35 CREATE TRIGGER

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2 The SQL Language : 2.3 SQL Commands : 2.3.35 CREATE TRIGGER

CREATE TRIGGER -- define a new trigger
[ REFERENCING { OLD AS old | NEW AS new } ...]
[ WHEN condition ]
{ WHEN exception [ OR exception ] [...] THEN
statement; [, ...] } [, ...]
CREATE TRIGGER defines a new trigger. CREATE OR REPLACE TRIGGER will either create a new trigger, or replace an existing definition.
If you are using the CREATE TRIGGER keywords to create a new trigger, the name of the new trigger must not match any existing trigger defined on the same table. New triggers will be created in the same schema as the table on which the triggering event is defined.
condition is a Boolean expression that determines if the trigger will actually be executed; if condition evaluates to TRUE, the trigger will fire.
If the trigger definition includes the FOR EACH ROW keywords, the WHEN clause can refer to columns of the old and/or new row values by writing OLD.column_name or NEW.column_name respectively. INSERT triggers cannot refer to OLD and DELETE triggers cannot refer to NEW.
If the trigger includes the INSTEAD OF keywords, it may not include a WHEN clause. A WHEN clause cannot contain subqueries.
REFERENCING { OLD AS old | NEW AS new } ...
REFERENCING clause to reference old rows and new rows, but restricted in that old may only be replaced by an identifier named old or any equivalent that is saved in all lowercase (for example, REFERENCING OLD AS old, REFERENCING OLD AS OLD, or REFERENCING OLD AS "old"). Also, new may only be replaced by an identifier named new or any equivalent that is saved in all lowercase (for example, REFERENCING NEW AS new, REFERENCING NEW AS NEW, or REFERENCING NEW AS "new").
Either one, or both phrases OLD AS old and NEW AS new may be specified in the REFERENCING clause (for example, REFERENCING NEW AS New OLD AS Old).
Determines whether the trigger should be fired once for every row affected by the triggering event, or just once per SQL statement. If specified, the trigger is fired once for every affected row (row-level trigger), otherwise the trigger is a statement-level trigger.
A variable, type, REF CURSOR, or subprogram declaration. If subprogram declarations are included, they must be declared after all other variable, type, and REF CURSOR declarations.
An SPL program statement. Note that a DECLARE - BEGIN - END block is considered an SPL statement unto itself. Thus, the trigger body may contain nested blocks.
An exception condition name such as NO_DATA_FOUND, OTHERS, etc.

2 The SQL Language : 2.3 SQL Commands : 2.3.35 CREATE TRIGGER

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