数据库练习题26-45题

--26、  查询存在有85分以上成绩的课程Cno.
select distinct Cno from Score where Degree >85

--27、查询出“计算机系“教师所教课程的成绩表。
select * from Score where Cno in ( select Cno from Course where Tno in ( select Tno from Teacher where Depart = '计算机系'))


--0028、查询“计算机系”与“电子工程系“不同职称的教师的Tname和Prof。
select Tname,Prof from Teacher t1 where Depart = '计算机系' and not exists (select * from Teacher t2 where Depart = '电子工程系' and t1.Prof = t2.prof)
union
select Tname,Prof from Teacher t1 where Depart = '电子工程系' and not exists (select * from Teacher t2 where Depart = '计算机系' and t1.Prof = t2.prof)

--0029、查询选修编号为“3-105“课程且成绩至少高于一个选修编号为“3-245”的同学的Cno、Sno和Degree,并按Degree从高到低次序排序。--any 任何一个值 , all 所有的数值
select * from Score where Degree >any( select Degree from Score where Cno='3-245') and Cno ='3-105'  order by  Degree desc

--30、查询选修编号为“3-105”且成绩高于选修编号为“3-245”课程的同学的Cno、Sno和Degree.
select * from Score where Degree > all(select Degree from Score where Cno='3-245') and Cno='3-105' 

--31、 查询所有教师和同学的name、sex和birthday.
    select Sname,Ssex,Sbirthday from Student
union
    select Tname,Tsex,Tbirthday from Teacher

--32、查询所有“女”教师和“女”同学的name、sex和birthday.
    select Sname,Ssex,Sbirthday from Student where Ssex='女'
union
    select Tname,Tsex,Tbirthday from Teacher where Tsex='女'

--33、 查询成绩比该课程平均成绩低的同学的成绩表。
    select * from Score s1 where Degree<(select AVG(degree) from Score s2 group by Cno having s1.Cno= s2.Cno)

--34、 查询所有任课教师的Tname和Depart.
    select Tname,Depart from Teacher where Tno in ( select Tno from Course where Cno in (select Cno from Score))

--35 、 查询所有未讲课的教师的Tname和Depart. 
    select Tname,Depart from Teacher where Tno not in ( select Tno from Course where Cno in (select Cno from Score))

--36、查询至少有2名男生的班号。--先选出所有男生，再按班级分组
    select Class from Student where Ssex='男' group by Class having COUNT(*)>1

--37、查询Student表中不姓“王”的同学记录。  
    select * from Student where Sname not like '王%'

--0038、查询Student表中每个学生的姓名和年龄。
     --注：year(getdate())获取当前时间“年” getdate()获取
    select Sname,year(getdate())-YEAR(Sbirthday) as age from Student 

--39、查询Student表中最大和最小的Sbirthday日期值。
     select MAX(Sbirthday),MIN(Sbirthday) from Student

--40、以班号和年龄从大到小的顺序查询Student表中的全部记录。
    select  *  from Student  order by Class desc,Sbirthday asc
 
--41、查询“男”教师及其所上的课程。
    select Cname,Tname from Course join Teacher on Course.Tno=Teacher.Tno where Tsex='男' --联合2个表格做法
    
select * from course where tno in(select tno from teacher where tsex='男')    --where做法

--42、查询最高分同学的Sno、Cno和Degree列。
    select Sno,Cno,Degree from Score where Degree =( select MAX(Degree) from Score )--方法一

    select top 1 * from score order by degree desc     --方法二

--43、查询和“李军”同性别的所有同学的Sname.
    select Sname from Student where Ssex=( select Ssex from Student  where Sname='李军') and Sname !='李军'

--44、查询和“李军”同性别并同班的同学Sname.
    select Sname from Student where Ssex=( select Ssex from Student  where Sname='李军') and Class=(select Class from Student where Sname='李军') and Sname !='李军' --方法一

select sname from student s1 where ssex=(
select ssex from student s2 where sname='李军' and s1.class= s2.class
)--方法二    

--45、查询所有选修“计算机导论”课程的“男”同学的成绩表。
    select * from Score where Cno=( select Cno from Course where Cname='计算机导论') and Sno in (select Sno from Student where Ssex='男')--f方法1