基于"学生-选课-课程"数据库中的三个关系:
S(S#,SNAME,SEX,BIRTHYEAR,DEPT),主码为S#
C(C#,CNAME,TEACHER),主码为C#
SC(S#,C#,GRADE),主码为(S#,C#)
查找"没有选修C02号课程的学生的姓名", 下列SQL语句中哪一个是错误的?
- A.SELECT SNAME FROM S WHERE NOT EXISTS (SELECT * FROM SC WHERE SC.S# = S.S# AND C# ='C02');
- B.SELECT SNAME FROM S WHERE EXISTS (SELECT * FROM SC WHERE SC.S# = S.S# AND C# <>'C02');
- C.SELECT SNAME FROM S WHERE S# NOT IN (SELECT S# FROM SC WHERE C# ='C02');
- D.SELECT SNAME FROM S WHERE S# IN (SELECT S# FROM S EXCEPT SELECT S# FROM SC WHERE C# ='C02');
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