SQL语句库联系
Studentdent(S#,Sname,Sage,Ssex) 学生表 Course(C#,Cname,T#) 课程表 SC(S#,C#,score) 成绩表 Teacher(T#,Tname) 教师表 1、查询“001”课程比“002”课程成绩高的所有学生的学号; Select a.s# from (select s#,score from sc where c#=‘001’) a join (select s#,socre from sc where c#=‘002’) b on a.s# = b.s# where a.score > b.score; 2、查询平均成绩大于60分的同学的学号和平均成绩; Select S#,avg(avg) from sc group by S# having avg(score)>60; 3、查询所有同学的学号、姓名、选课数、总成绩; Select Student.S#,Student.sname,count(C#),sum(score) from Studentdent Student join sc s on Student.S# = s.S# 4、查询姓“李”的老师的个数; select count(T#) from teacher where tname like ‘李%’; 5、查询没学过“叶平”老师课的同学的学号、姓名;