基于教材上的学生表Student、课程表Course和选课表SC，查找所有比学生“王华”年龄大的学生姓名、年龄和性别，正确的SQL语句是________。
A. SELECTSname, Sage, Ssex FROMStudentWHERE Sage > ( SELECT Sage FROM Student WHERESname = '王华' )
B. SELECTSname, Sage,Ssex FROM Student WHERESname = '王华'
C. SELECTSname, Sage,Ssex FROMStudentWHERE Sage > ( SELECT Sage WHERESname = '王华' )
D. SELECTSname, Sage,SsexFROM StudentWHERE Sage > '王华'.Sage
基于教材上的选课表SC，使用嵌套查询查找所有超过所选课程平均分的学生选课记录，正确的SQL语句是________。
A. SELECTSno, Cno, Grade FROMSC SC1WHERE Grade>(SELECT AVG(Grade) FROMSC SC2);
B. SELECTSno, Cno, Grade FROMSC SC1WHERE Grade>(SELECT AVG(Grade) FROMSC SC2 WHERE SC2.Cno=SC1.Cno);
C. SELECTSno, Cno, Grade FROMSC SC1WHERE Grade>(SELECT AVG(Grade) FROMSC SC2 GROUP BY SC2.Cno);
D. SELECTSno, Cno, Grade FROMSC SC1WHERE AVG(Grade)>(SELECT Grade FROMSC SC2 WHERE SC2.Cno=SC1.Cno);
现有学生关系表S(sno，sname，ssex，sage），查找年龄比某个女生小的男生信息，对应的SQL语句是________。
A. select * fromSwhere ssex='男' and sage in(select sage from S where ssex='女');
B. select * fromSwhere ssex='男' and sage<(select sage from S where ssex='女');
C. select * fromSwhere ssex='男' and sage D. select * fromSwhere ssex='男' and sage
现有学生关系表S(sno，sname，ssex，sage）和选修关系表SC(sno, cname, grade)，查找没有选修"数据库"课程的学生个人信息，对应的SQL语句是________。
A. select*fromS where exists(select * from SC where SC.sno=S.sno and SC.cname<>'数据库 );
B. select*fromS where exists(select * from SC where SC.sno<>S.sno and SC.cname='数据库 );
C. select*fromS where not exists(select * from SC where SC.sno=S.sno and SC.cname<>'数据库 );
D. select*fromS where not exists(select * from SC where SC.sno=S.sno and SC.cname='数据库 );
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