20)设有订单表order(其中包括字段:订单号,客户号,职员号,签订日期,金额),查詢2007年所签订单的信息,并按金额降序排序,正确的SQL命令是:
(A) SELECT * FROM order WHERE YEAR(签订日期)=2007 ORDER BY 金额 DESC (B) SELECT * FROM order WHILE YEAR(签订日期)=2007 ORDER BY 金额 ASC (C) SELECT * FROM order WHERE YEAR(签订日期)=2007 ORDER BY 金额 ASC (D) SELECT * FROM order WHILE YEAR(签订日期)=2007 ORDER BY 金额 DESC