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查询“001”课程比“002”课程成绩高的所有学生的学号
SELECT tblstudent.StuId
from tblstudent
where
(SELECT TC.Score FROM tblscore TC WHERE TC.CourseId='001'and tblstudent.StuId=tc.StuId)
>
(SELECT tb.Score FROM tblscore Tb WHERE Tb.CourseId='002' and tblstudent.StuId=Tb.StuId)
查询平均成绩大于60分的同学的学号和平均成绩
select Student.stuId,avg(Scores.score)
from Student,Scroes
where Studen.stuId=Scores.stuId
Group by Student.stuId
having avg(Scores.score)>60;
聚合函数是不能连接在where子句后面的。
查询所有同学的学号,姓名,选课数,总成绩
Select StuId,StuName,
(Select Count(CourseId) From tblScore t1 Where t1.StuId=s1.StuId)SelCourses,
(Select Sum(Score) From tblScore t2 Where t2.StuId=s1.StuId) SumScore
From tblStudent s1
查询姓李的老师的个数
select count(Teacher.TeacherId)
from Teacher
where Teacher.TeacherName like "李%";
查询所有课程成绩小于60分的 同学的学号,姓名
select tblstudent.StuId,tblstudent.StuName
from tblstudent
where tblstudent.StuId NOT IN
(select tblscore.StuId from tblscore where tblstudent.StuId=tblscore.StuId AND tblscore.Score>60)
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