Os clientes que têm cupons com o valor de 500 são maus ou bons?
CREATE TABLE discount_coupons (coupon_id VARCHAR, coupon_amount VARCHAR); CREATE TABLE customers (good_or_bad_customer VARCHAR, coupon_id VARCHAR)
SELECT T1.good_or_bad_customer FROM customers AS T1 JOIN discount_coupons AS T2 ON T1.coupon_id = T2.coupon_id WHERE T2.coupon_amount = 500