题目内容
（请给出正确答案）
设学生选课关系模式为SC(Sno，Cno，Grade)，其中，Sno为学号，Cno为课程号， Grade为成绩，SQL查询语句如下：
SELECT Sno
FROMSC SCX
WHERE NOT EXISTS
(SELECT*
FROM SC SCY
WHERE SCY.Sno='1042'AND NOT EXISTS
(SELECT *
FROMSCSCZ
WHERE SCZ.Sno=SCX.Sno AND SCZ.Cno=SCY.Cno))；与该查询等价的元组演算表达式为{t|(13)(SC(u)∧SC(v)∧(14)∧t[1]= u[1])}。
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更多“设学生选课关系模式为SC（Sno，Cno，Grade)，其中…”相关的问题
A、select sno from sc where grade>90 group by sno having count(cno)>2
B、select sno from sc where grade>90 group by sno having count( distinct sno)>2
C、select sno from sc where grade>90 group by sno having count(*)>2
D、select sno from sc where grade>90 and count(*)>2 group by sno
A、πS#，C#（SC）÷πC#（σTNAME='LIU'（SC）） SELECT DISTINCT S# FROM SC AS X WHERE NOT EXISTS (SELECT * FROM C WHERE TNAME=’LIU’ AND NOT EXISTS (SELECT * FROM SC AS Y WHERE Y.S#=X.S# AND Y.C#=C.C#));
B、πS#，C#（SC）÷πC#（σTNAME='LIU'（C）） SELECT DISTINCT S# FROM SC AS X WHERE NOT EXISTS (SELECT * FROM C WHERE TNAME=’LIU’ AND NOT EXISTS (SELECT * FROM SC AS Y WHERE Y.S#=X.S# AND Y.C#=C.C#));
C、πS#，C#（SC）÷πC#（σTNAME='LIU'（C）） SELECT DISTINCT S# FROM SC AS X WHERE NOT EXISTS (SELECT * FROM C WHERE TNAME=’LIU’ AND EXISTS (SELECT * FROM SC AS Y WHERE Y.S#=X.S# AND Y.C#=C.C#));
D、πS#，C#（SC）÷πC#（σTNAME='LIU'（C）） SELECT DISTINCT S# FROM SC WHERE NOT EXISTS (SELECT * FROM C WHERE TNAME=’LIU’ AND EXISTS (SELECT * FROM SC AS Y WHERE Y.S#=X.S# AND Y.C#=C.C#));
A、SELECT SNO, SUM (GRADE) AS SUM_GRADE FROM SC GROUP BY SNO ORDER BY SUM_GRADE DESC HAVING COUNT(*) >= 4;
B、SELECT SNO, SUM (GRADE) AS SUM_GRADE FROM SC GROUP BY SNO HAVING COUNT(*)>=4 ORDER BY SUM_GRADE DESC;
C、SELECT SNO, SUM (GRADE) AS SUM_GRADE FROM SC HAVING COUNT(*)>=4 GROUP BY SNO ORDER BY SUM_GRADE DESC;
D、SELECT SNO, SUM (GRADE) AS SUM_GRADE FROM SC ORDER BY SUM_GRADE DESC GROUP BY SNO HAVING COUNT(*)>=4;
A、SELECT SNO, SNAME, SAGE, SSEX, SDEP FROM S WHERE SDEP IN (SELECT SDEP FROM S WHERE SNO = '20180601011');
B、SELECT * FROM S WHERE SDEP IN (SELECT SDEP FROM S WHERE SNO = '20180601011');
C、SELECT SNO, SNAME, SAGE, SSEX, SDEP FROM S WHERE SNO = '20180601011';
D、SELECT S1.SNO, S1.SNAME, S1.SAGE, S1.SSEX, S1.SDEP FROM S S1, S S2 WHERE S1.SDEP = S2.SDEP AND S2.SNO = '20180601011';
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