题目内容

查询所有选修了数学（课程号为2）的学生姓名，不正确的查询语句是：（）

A. SELECT Student.SnameFROM Student, SCWHERE Student.Sno = SC.SnoAND SC.Cno = 2;
B. SELECT Student.SnameFROM StudentLEFT JOIN SCON Sno = Student.SnoWHERE SC.Cno = 2;
C. SELECT Student.SnameFROM StudentWHERE Sno In (SELECT SnoFROM SCWHERE Cno = 2);
D. SELECT SnameFROM SCLEFT JOIN StudentON Student.Sno = SC.SnoWHERE SC.Cno = 2;

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集合操作可用来连接两个结果集，所有的集合操作语句都可以转换成不含集合操作的单语句查询。

A. 对
B. 错

连接查询必须涉及到至少两张不同的表。

A. 对
B. 错

查询计算机系任意学生选修过的课程号，可以使用如下语句：SELECT DISTINCT CnoFROM SCWHERE Sno IN (SELECT SnoFROM StudentWHERE Sdept = 'CS');

A. 对
B. 错

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