sql´¥·¢Æ÷ µ±Ä³¸ö×ֶεÄÖµ´Óij¸öÊý×Ö±ä³É0£¬ÄÇô°Ñ¸Ã×ֶαäΪ255

CREATE
TRIGGER `´¥·¢Æ÷Ãû` BEFORE UPDATE ON `±íÃû`
FOR EACH ROW BEGIN
IF old.effec_number <> 0 AND new.effec_number = 0 THEN
SET new.effec_number = 255;
END IF;
END;