excerpt from the mysql manual --
Code:
CREATE
[DEFINER = { user | CURRENT_USER }]
TRIGGER trigger_name trigger_time trigger_event
ON tbl_name FOR EACH ROW trigger_stmt
trigger_event indicates the kind of statement that activates the trigger. The
trigger_event can be one of the following:
INSERT: The trigger is activated whenever a new row is inserted into the table; for example, through INSERT, LOAD DATA, and REPLACE statements.
UPDATE: The trigger is activated whenever a row is modified; for example, through UPDATE statements.
DELETE: The trigger is activated whenever a row is deleted from the table; for example, through DELETE and REPLACE statements.