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设有学生关系S(Sno, Sname, Sage),课程关系C(Cno, Cname),选修关系SC(Sno, Cno, Grade),其中Sno是学号,Sname是学生姓名,Sage是学生年龄,Cno是课程号,Cname是课程名,Grade是成绩。要查询选修了“ACCESS”课程的年龄不小于20的全体学生姓名,可用SELECT SNAME FROM S, C, SC WHERE 语句实现。
A、S.Sno=SC.Sno and C.Cno=SC.Cno and Sage >=20 and Cname = ‘ACCESS‘
B、S.Sno=SC.Sno and C.Cno=SC.Cno and Sage in >=20 and Cname in ‘ACCESS‘
C、Sage in >=20 and Cname in ‘ACCESS‘
D、Sage in >=20 and Cname = ‘ACCESS‘