【简答题】根据某些条件对一个关系作水平分解,选择符合条件的元组组成一个新的关系,这样的操作称为( )。 A)投影 B)选择 C)等值连接 D)自然连接
【单选题】根据某些条件对一个关系作水平分解,选择符合条件的元组组成一个新的关系,这样的操作称为
【单选题】听力原文:W: Michael, would you like to eat out tonight? M: Oh, I'd really like to, but I have promised my sister to see a movie with her tonight. Q: What will the man do this evening? (4)
B.
To eat out with the woman.
C.
To see a movie with his sister.
D.
To eat out with his sister.
【单选题】— I like speaking better than listening in English learning. —Oh, really? I think you should be good at of them.
【简答题】根据某些条件对一个关系作水平分解,选择符合条件的元组组成一个新的关系,这样的操作称为( )。 A)投影 B)选择 C)等值连接 D)自然连接
【单选题】–I am twelve and I like English. -- Oh, really? I am twelve and I like English.
【单选题】根据某些条件对一个关系作水平分解,选择符合条件的元组组成一个新的关系,这样的操作系称为