SQL中，使用DROP TABLE 语句删除某个基本表时，不能被自动删除的是

A.INSERT INTO

B.UPDATE TABLE

C.ALTER TABLE

D.DROP TABLE

A.INSERT INTO

B.UPDATE TABLE

C.ALTER TABLE

D.DROP TABLE

A.INSERT INTO

B.UPDATE TABLE

C.ALTER TABLE

D.DROP TABLE

A.ALTER TABLE

B.DROP TABLE

C.DELETE TABLE

D.KILL TABLE

A.ALTER TABLE

B.KILL TABLE

C.DELETE TABLE

D.DROP TABLE

A.ALTER TABLE

B.KILL TABLE

C.DELETE TABLE

D.DROP TABLE

A.ALTER TABLE

B.DROP TABLE

C.DELETE TABLE

D.KILL TABLE

A.DELETE TABLE S

B.DELETE S

C.DROP TABLE S

D.DROP S

根据SQL标准，删除表student中对字段sno的唯一性约束，应该使用下面哪条语句？ ()

A drop sno from table student

B alter table student drop sno

C alter table student drop unique(sno)

D alter table student drop sno unique

把表中"单价"字段的有效性规则取消,使用SQL语句

A．ALTER TABLE ORDER ALTER 单价 DROP CHECK

B．ALTER TABLE ORDER DELETE 单价 DROP CHECK

C．ALTER TABLE ORDER DELETE CHECK 单价

D．ALTER TABLE ORDER DROP CHECK 单价