![](https://lstatic.shangxueba.com/jiandati/h5/images/m_q_title.png)
[单选题]
有两个关系R和S,分别包含15个和10个元组,则在R∪S,R-S,R∩S中不可能出现的元组数目情况是
A.15,5,10
B.18,17,7
C.21,11,4
D.25,15,0
提问人:网友wl36978
发布时间:2022-01-07
A.15,5,10
B.18,17,7
C.21,11,4
D.25,15,0
有两个关系R和S,分别包含15个和10个元组,则在, R-S,
中不可能出现的元组数目情况是( )
A、15, 5, 10
B、18, 7, 7
C、21, 11, 4
D、21, 11, 4
A、SELECT * FROM Movie WHERE director LIKE ‘_a_’;
B、SELECT * FROM Movie WHERE director LIKE ‘%a%’;
C、SELECT * FROM Movie WHERE director LIKE ‘%a_’;
D、SELECT * FROM Movie WHERE director LIKE ‘_a%’
为了保护您的账号安全,请在“简答题”公众号进行验证,点击“官网服务”-“账号验证”后输入验证码“”完成验证,验证成功后方可继续查看答案!