http://stackoverflow.com/questions/2115497/check-constraint-in-mysql-is-not-working
mysql的check约束问题
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mysql的check约束问题
delimiter //
mysql> CREATE TRIGGER trig_sd_check BEFORE INSERT ON Customer
-> FOR EACH ROW
-> BEGIN
-> IF NEW.SD<0 THEN
-> SET NEW.SD=0;
-> END IF;
-> END
-> //
mysql> delimiter ;