30.设有学生S（学号，姓名，性别，年龄），查詢所有年龄小于等于18岁的女同学，并按年龄进行降序排序生成新的表WS，正确的SQL命令是
(A) SELECT * FROM S WHERE 性别=’女’ AND 年龄<=18 ORDER BY 4 DESC INTO TABLE WS
(B) SELECT * FROM S WHERE 性别=’女’ AND 年龄<=18 ORDER BY 年龄 INTO TABLE WS
(C) FROM S WHERE 性别=’女’ AND 年龄<=18 ORDER BY ‘年龄’ DESC INTO TABLE WS
(D)FROM S WHERE 性别=’女’ AND 年龄<=18 ORDER BY ‘年龄’ ASC INTO TABLE WS