查看下面PROMOTIONS表結(jié)構(gòu):
管理層想看到每種促銷(xiāo)種類(lèi)的唯一促銷(xiāo)成本。下面哪個(gè)查詢(xún)得到需要的結(jié)果()
A.SELECT.DISTINCT.promo_cost,promo_category.FROM.promotions
B.SELECT.promo_category,DISTINCT.promo_cos.tFROM.promotions
C.SELECT.DISTINCT.promo_cost,DISTINCT.promo_category.FROM.promotions
D.SELECT.DISTINCT.promo_category,promo_cost.FROMpromotions.ORDERBY1