To erase a column in a table, we use the command in SQL:
A.Delete
B.Alter
C.Erase
D.Update
A.Delete
B.Alter
C.Erase
D.Update
A、Employeeid和depid设为组合主键
B、Employeeid设为主键,同时在depid列上创建一个外键约束
C、Employeeid设为主键,同时在depid列上创建一个检查约束
D、在Employeeid列上创建一个唯一约束,同时在depid列上创建一个外键约束
B、4 5 5 6
C、1 3 2 4
D、3 4 6 8
A、GRANT UPDATE(balance) ON account TO Zhang ;
B、GRANT UPDATE balance OF account TO Zhang ;
C、REVOKE UPDATE(balance) ON account TO Zhang ;
D、REVOKE UPDATE balance OF account FROM Zhang ;
A、Entity integrity
B、Referential integrity
C、Check constraint
D、User defined constraint
A、GRANT
B、REVOKE
C、CREATE
D、GIVE
A、MAX( )
B、MIN( )
C、AVG( )
D、COUNT( )
B、MIN( )
C、AVG( )
D、COUNT( )
A、SELECT
B、FROM
C、WHERE
D、GROUP BY
A、undo(T0) & undo (T1)
B、undo(T0) & redo (T1)
C、redo(T0) & undo (T1)
D、redo(T0) & redo (T1)
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