以下删除表正确的( )
A.Delete * from emp
B.Drop database emp
C.Drop * from emp
D.delete database emp

以下哪种操作能够实现实体完整性( ) A.设置唯一键 B.设置外键 C.减少数据冗余 D.设置主键

A.设置唯一键
B.设置外键
C.减少数据冗余
D.设置主键

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以下哪项用来排序( ) A.ORDERED BY B.ORDER BY C.GROUP BY D.GROUPED BY

A.ORDERED
B.ORDER
C.GROUP
D.GROUPED

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