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sql语句中较为重要的查询逻辑

2015-03-02 17:52 302 查看

较复杂的SQL例句

S(Sno,Sname,Sage,Sdept, Ssex) 学生表

C(Cno,Cname,Teacher) 课程表

SC(Sno,Cno,score) 成绩表

1、查询“001”课程比“002”课程成绩低的所有学生的学号；

  select a.Sno from (select sno, score from SC where Cno='001') a, (select sno, score from SC where Cno='002') b where a.score<b.score and a.sno=b.sno;

2、查询平均成绩大于60分的同学的学号和平均成绩；

    select Sno,avg(score) from sc group by Sno having avg(score) >60;

3、查询姓“高”的老师的个数；

  select count(distinct(Teacher)) from C where Teacher like '高%';

4、查询没学过“XXXX”老师课的同学的学号、姓名；

    select S.Sno,S.Sname from S where Sno not in (select distinct( SC.Sno) from SC, C where SC.Cno=C.Cno and C.Teacher='XXXX');

5、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；

select S.Sno, S.Sname from S, SC where S.Sno=SC.Sno and SC.Cno='001'and exists ( Select * from SC as SC_2 where SC_2.Sno=SC.Sno and SC_2.Cno='002');

6、查询学过“XXXX”老师所教的所有课的同学的学号、姓名；

Select Sno,Sname from S where Sno in (select Sno from SC, C where SC.Cno=C.Cno and C.Teacher='XXXX' group by Sno having count(SC.Cno)=(select count(Cno) from C where Teacher='XXXX'))

8、查询课程编号“002”的成绩比课程编号“001”课程高的所有同学的学号、姓名；

  Select Sno,Sname from (select S.Sno, S.Sname, score, (select score from SC SC_2 where SC_2.Sno=S.Sno and SC_2.Cno='002') score2 from S, SC where S.Sno=SC.Sno and Cno='001') S_2  where score2 >score;

9、查询所有课程成绩大于60分的同学的学号、姓名；

  select Sno,Sname from S where Sno not in (select S.Sno from S, SC where S.Sno=SC.Sno and score<60);

10、查询没有学全所有课的同学的学号、姓名；

select S.Sno, S.Sname from S,SC where S.Sno=SC.Sno group by S.Sno having count(Cno) <(select count(Cno) from C)

11、查询至少有一门课与学号为“95001”的同学所学相同的同学的学号和姓名；

select S.Sno,S.Sname from S,SC where S.Sno=SC.Sno and Cno in (select Cno from SC where Sno='95001')

12、查询至少学过学号为“95001”同学所有一门课的其他同学学号和姓名；

select distinct SC.Sno,Sname from S,SC where S.Sno=SC.Sno and Cno in (select Cno from SC where Sno='95001')

这是大学期间，老师给的数据库查询参考，对于现在不断在编程语言中进取的人来说保证看过上面的所有查询逻辑肯定会有更新的认识。个人甚至可以肯定的说，个人的数据库水平仍旧没有突破上面12条查询语句所提供的逻辑，希望这里将高老师的智慧分享一下。

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标签： database sql mysql select avg

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