工作SQL小结

 SELECT SUM(IFNULL(mc.coupon_nominal_value,0)*IFNULL(mc.coupon_count,0)) AS couponCount, 		SUM( IFNULL(mc.coupon_count,0)) AS couponNum , 		m.merchant_name AS merchantName, 		mc.merchant_id AS merchantId,		mc.merchant_coupon_id,		mcs.merchant_coupon_specification_name AS mcsName		FROM backend.merchant_coupon mc 		JOIN backend.merchant m ON m.merchant_id=mc.merchant_id 		JOIN backend.merchant_coupon_specification mcs ON mcs.merchant_coupon_specification_id=mc.coupon_specification_id 		WHERE mc.is_deleted=0 		AND mc.coupon_nominal_value>0 AND mc.coupon_count>0 		GROUP BY merchantId,mcsName						SELECT COUNT(DISTINCT mc.coupon_specification_id,mc.merchant_id) FROM backend.merchant_coupon mc                  WHERE mc.is_deleted=0            AND mc.coupon_nominal_value>0 AND mc.coupon_count>0