[MySQL]使用EXISTS代替IN

Posted 2020-10-12

#IN -> EXISTS
SELECT * FROM CouponItem AS A WHERE A.CouponId IN(SELECT B.Id FROM Coupon AS B WHERE B.Id<30);
SELECT * FROM CouponItem AS A WHERE EXISTS(SELECT B.Id FROM Coupon AS B WHERE B.Id<30 AND A.CouponId=B.Id);

#NOT IN -> NOT EXISTS
SELECT * FROM CouponItem AS A WHERE A.CouponId NOT IN(SELECT B.Id FROM Coupon AS B WHERE B.Id<30);
SELECT * FROM CouponItem AS A WHERE NOT EXISTS(SELECT B.Id FROM Coupon AS B WHERE B.Id<30 AND A.CouponId=B.Id);