【判断题】【消耗次数：1】
视图是关系数据库系统提供给用户以多种角度观察数据库中的数据的重要机制。
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正确
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错误
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相关题目
【单选题】
数据库DB、数据库系统DBS、数据库管理系统DBMS之间的关系是（ ）
①
DB包含DBS和DBMS
②
DBMS包含DB和DBS
③
DBS包含DB和DBMS
④
没有任何关系
随机题目
【单选题】
He thought that _____.
①
the effort doing the job was not worth.
②
the effort was not worth in doing the job.
③
it was not worth the effort doing the job.
④
it was not worth the effort by doing the job.
【单选题】
15. While I like the dress very much, I cant afford it. The word “while” means ______.
①
when
②
although
③
as long as
④
whereas
【单选题】
You _____ her in her office last Friday, she’s been out of town for two weeks.
①
needn’t have seen
②
must have seen
③
might have seen
④
can’t have seen