使用 SQL PL 的 BEFORE INSERT 触发器

CREATE TRIGGER business_rules
BEFORE INSERT ON empprojact
REFERENCING NEW AS n
FOR EACH ROW
  BEGIN ATOMIC
  -- Business Rule One (Project ending date Can't be NULL)
  IF (n.emendate IS NULL) THEN
     SET n.emendate = CURRENT date;
  END IF;

  -- Business Rule Two (Project ending date Can't end in last month of the year)
  IF (n.emendate BETWEEN '2009-12-01' AND '2009-12-31') THEN
     SIGNAL SQLSTATE '90000'
        SET MESSAGE_TEXT = 'Business Rule violation - 90000';
  END IF;

  END!