A.SELECT*FROM客户WHERE客户号!=(SELECT客户号FROM订单)
B.SELECT*FROM客户WHERE客户号!=ANY(SELECT客户号FROM订单)
C.SELECT*FROM客户WHERE客户号NOTIN(SELECT客户号FROM订单)
D.SELECT*FROM客户WHERENOTEXISTS(SELECT*FROM订单WHERE客户号!=客户.客户号)