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关系的完整性一般不包括()
A.实体完整性规则
B.参照完整性规则
C.自定义完整性规则
D.事务完整性
A.实体完整性规则
B.参照完整性规则
C.自定义完整性规则
D.事务完整性
A、SELECT mID,year,director FROM Movie
B、SELECT mID,title,director FROM Movie
C、SELECT mID,title FROM Movie
D、SELECT mID,title,year,director FROM Movie
A、均不做参照完整性检查,可以随意更新两个表中的连接字段值
B、若Rating表中有相关参照记录,则Reviewer表的更新操作被禁止,Movie表的更新操作同时自动更新Rating表中记录的对应参照字段
C、若Rating表中有相关参照记录,则Reviewer表的更新操作同时自动更新Rating表中记录的对应参照字段,Movie表的更新操作被禁止
D、若Rating表中有相关参照记录,则均两个表的更新操作均被禁止
A、starts+20
B、stars*20
C、mID,stars*20
D、mID,stars+20
A、SELECT year,director FROM Movie
B、SELECT mID,title FROM Movie
C、SELECT director,year FROM Movie
D、SELECT director,mID FROM Movie
A、SELECT title FROM Movie WHERE year >= ‘1999’ and director == ‘Cameron’;
B、SELECT title FROM Movie WHERE year >= ‘1999’ and director = ‘Cameron’;
C、SELECT title FROM Movie WHERE year > ‘1999’ and director == ‘Cameron’;
D、SELECT title FROM Movie WHERE year > ‘1999’ and director = ‘Cameron’;
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