用SQL语言完成以下各项操作设有如下所示的关系SS#SNAMEAGESEX、CC#CNAMETEACHER和SCS#C#GRADE用SQL语句表示以下查询。1检索选修课程名称为MATHS的学生的学号与姓名2检索至少学习了课程号为C1和C2的学生的学号3检索年龄在18到20之间含18和20的女生的学号、姓名和年龄4检索平均成绩超过80分的学生学号和平均成绩5检索选修了全部课程的学生姓名

(1) SELECT S#, SNAME FROM S WHERE S# IN (SELECT S# FROM SC WHERE C# = 'MATHS') (2) SELECT S# FROM SC WHERE C# IN ('C1', 'C2') GROUP BY S# HAVING COUNT(DISTINCT C#) = 2 (3) SELECT S#, SNAME, AGE FROM S WHERE AGE BETWEEN 18 AND 20 AND SEX = 'F' (4) SELECT S#, AVG(GRADE) AS AVERAGE_GRADE FROM SC GROUP BY S# HAVING AVG(GRADE) > 80 (5) SELECT SNAME FROM S WHERE NOT EXISTS (SELECT C# FROM C WHERE NOT EXISTS (SELECT S# FROM SC WHERE S.S# = SC.S# AND C.C# = SC.C#))