的还有:Р--1.РSELECT Sname FROM StudentРWHERE (select o) from course)Р =(SELECT count(sno) FROM Grade Р GROUP BY Sno) Р Р--2.РSELECT Sname FROM StudentРWHERE Sno=ANYР(SELECT Sno FROM GradeР GROUP BY SnoР HAVING(COUNT(*)=Р (SELECT COUNT(*) FROM Course)))РORDER BY Sname;Р(1)查询选修了3号课程的学生学号及成绩,并按成绩的降序排列Р select Sno,Gmark from GradeР o='3'Р order by Gmark desc;Р(2)查询全体学生信息,要求查询结果按班级号升序排列,同一班级学生按年龄降序排列Р select * from StudentР order by Clno,Sage desc;Р(3)求每个课程号及其相应的选课人数Р o,count(Sno) as 选课人数 from Grade Р group o;Р(4)查询选修了3门以上课程的学生学号Р select Sno,o) as 选课门数 from GradeР group by SnoР having o)>3;Рselect sno from Grade gРwhere (select o) from Grade Р?where Sno=g.SnoР?)>3;Р五、思考题:Р用UNION或UNION ALL将两个SELECT命令结合为一个时,结果有何不同?Р当既能用连接词查询又能用嵌套查询时,应该选择哪种查询较好?为什么?Р库函数能否直接使用在:SELECT选取目标、HAVING子句、WHERE子句、GROUP BY列名中?
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