实验七 T-SQL语句高级应用（一）

实验七 T-SQL语句高级应用（一）


1、实验目的

（1）掌握多表连接查询、子查询的基本概念

（2）掌握多表连接的各种方法，包括内连接、外连接、交叉连接等

（3）掌握子查询的方法，包括相关子查询和不相关子查询。

2、实验内容

（1）查询所有班级的期末成绩平均分，并按照平均分降序排列

（2）查询教师基本信息和教授课程信息，其中包括未分配课程的教师信息

（3）查询‘090501’班级中选修了‘韩晋升’老师讲授的课程的学生的学号、姓名、课程名和期末成绩

（4）查询每门课程的课程号、课程名和选修该课程的学生人数，并按所选人数升序排序

（5）查询两门及以上课程的期末成绩超过80分的学生的姓名及平均成绩。

（6）查询“C语言”课程期末成绩比“电子技术”课程期末成绩高的所有学生的学号和姓名。

（7）查询所有班级期末平均成绩的最高分，并将其值赋给变量，通过PRINT语句输出。

（8）查询至少选修了姓名为“韩吟秋”的学生所选修课程中一门课的学生的学号和姓名。

--查询所有班级的期末成绩平均分，并按照平均分降序排列

select classno,avg(final) as '平均分'

from student,score

where student.studentno = score.studentno

group by student.classno

order by 平均分 desc

--查询教师基本信息和教授课程信息，其中包括未分配课程的教师信息

select teacher.*,course.cname

from teacher,course,teach_class

where teacher.teacherno = teach_class.teacherno and

teach_class.courseno = course.courseno

--查询‘090501’班级中选修了‘韩晋升’老师讲授的课程的学生的学号、姓名、课程名和期末成绩

select student.studentno,student.sname,course.cname,score.final

from student,course,score

where student.studentno = score.studentno and

course.courseno = score.courseno and

student.classno = '090501' and

course.courseno in

(

select teach_class.courseno

from teacher,teach_class

where teacher.teacherno = teach_class.teacherno and

teacher.tname = '韩晋升'

)

--查询每门课程的课程号、课程名和选修该课程的学生人数，并按所选人数升序排序

select course.courseno,course.cname,count(*) as '学生人数'

from course,student,score

where student.studentno = score.studentno and

course.courseno = score.courseno

group by course.courseno , course.cname

order by 学生人数 asc

--查询两门及以上课程的期末成绩超过80分的学生的姓名及平均成绩。

select student.sname,avg(final) as '平均成绩'

from student,score

where final >80 and

student.studentno = score.studentno

group by student.studentno,student.sname

having count(* ) >= 2



--查询“C语言”课程期末成绩比“电子技术”课程期末成绩高的所有学生的学号和姓名。

select test1.studentno,test1.sname from(

select student.studentno,sname,final

from student,score,course

where student.studentno = score.studentno and

score.courseno = course.courseno and

course.cname = N'C语言'

) as test1,(

select student.studentno,sname,final

from student,score,course

where student.studentno = score.studentno and

score.courseno = course.courseno and

course.cname = N'电子技术'

) as test2

where test1.final > test2.final and test1.studentno = test2.studentno

/*

select student.studentno ,student.sname ,score.final

into cc

from student,score,course

where student.studentno = score.studentno and

score.courseno = course.courseno and

cname =N'C语言'

select student.studentno ,student.sname ,score.final

into ca

from student,score,course

where student.studentno = score.studentno and

score.courseno = course.courseno and

cname =N'电子技术'

select cc.studentno ,cc.sname

from ca,cc

where ca.sname = cc.sname and

cc.final>ca.final

*/



--查询所有班级期末平均成绩的最高分，并将其值赋给变量，通过PRINT语句输出。

declare @high float



set @high =

(select top 1 tt.high from(

select avg(final) as 'high'

from student,score,course

where student.studentno = score.studentno and

score.courseno = course.courseno

group by student.classno

)as tt

)

print cast(@high as varchar(30))

select @high

--查询至少选修了姓名为“韩吟秋”的学生所选修课程中一门课的学生的学号和姓名。

select student.studentno,sname

from student,teach_class

where student.classno = teach_class.classno and

student.sname != N'韩吟秋' and

teach_class.classno in

(

select teach_class.classno

from teach_class,teacher,student

where

teacher.teacherno = teach_class.teacherno and

student.sname = N'韩吟秋' and

student.classno = teach_class.classno

)

group by sname,student.studentno