1、查询“张旭“教师任课的学生成绩。
-- 方法一
select *
from score
where cno = (select cno from course where tno =(select tno from teacher where tname ='张旭'))
-- 方法二
select sc.*
from teacher t , course c, score sc
where t.tno = c.tno and c.cno = sc.cno and t.tname ='张旭'
-- 方法三
select sc.*
from teacher t join course c join score sc
on t.tno = c.tno and c.cno = sc.cno
where t.tname ='张旭'
-- 方法四
select sc.*
from teacher t inner join course c inner join score sc
on t.tno = c.tno and c.cno = sc.cno
where t.tname ='张旭'
-- 方法五
select sc.*
from teacher t inner join course c inner join score sc
on t.tno = c.tno and c.cno = sc.cno and t.tname ='张旭'
2、查询选修某课程的同学人数多于5人的教师姓名。
-- 方法一
select tname
from teacher
where tno in (select tno from course where cno in (select cno from score group by CNO having count(cno) > 5))
-- 方法二
select t.tname
from teacher t join course c join score sc
on t.tno = c.tno and c.cno = sc.cno
group by sc.CNO
having count(sc.cno) > 5
-- 方法三
select t.tname
from teacher t inner join course c inner join score sc
on t.tno = c.tno and c.cno = sc.cno
group by sc.CNO
having count(sc.cno) > 5
-- 方法四
select t.tname
from teacher t , course c , score sc
where t.tno = c.tno and c.cno = sc.cno
group by sc.CNO
having count(sc.cno) > 5
3、查询95033班和95031班全体学生的记录。
-- 方法一
select *
from student
where class = '95033' or class ='95031'
-- 方法二
select *
from student
where class in ('95033' ,'95031')
4、查询存在有85分以上成绩的课程Cno。
-- 方法一
select cno
from score
where degree >=85
group by cno
-- 方法二
select DISTINCT cno
from score
where degree >=85
5、查询所有教师和同学的name、sex和birthday
-- 方法一
select distinct Sname as name,Ssex as sex,Sbirthday as birthday from student
union
select distinct Tname as name,Tsex as sex,Tbirthday as birthday from Teacher
-- 方法二
select tname name,tsex sex, tbirthday birthday
from teacher
union
select sname name,ssex sex, sbirthday birthday
from student
6、查询所有“女”教师和“女”同学的name、sex和birthday。
-- 方法一
select tname name,tsex sex, tbirthday birthday
from teacher
where tsex ='女'
union
select sname name,ssex sex, sbirthday birthday
from student
where ssex ='女'
-- 方法二
select tname as name,tsex as sex, tbirthday as birthday from teacher where tsex ='女'
union
select sname as name,ssex as sex, sbirthday as birthday from student where ssex ='女'
7、查询成绩高于选修编号为“3-245”课程的同学的Cno、Sno和Degree
-- 方法一
select cno,sno,degree
from score
where degree > (select min(degree) from score where cno ='3-245') and cno !='3-245'
order by degree desc
-- 方法二
select cno,sno,degree
from score
where degree > (select min(degree) from score where cno ='3-245') and cno <>'3-245'
order by degree desc
8、查询选修编号为“3-105“课程且成绩至少高于选修编号为“3-245”的同学的Cno、Sno和Degree,并按Degree从高到低次序排序。
select cno ,sno,degree
from score
where degree > (select min(degree) from score where cno ='3-245') and cno ='3-105'
order by degree desc
9、查询“计算机系”中的与“电子工程系“不同职称的教师的Tname和Prof。
select tname,prof
from teacher
where prof not in (select prof from teacher where depart='电子工程系' and prof in (select prof from teacher where depart='计算机系'))
and depart in ('计算机系','电子工程系')
10、查询出“计算机系“教师所教课程的成绩表
-- 方法一
select *
from score
where cno in (select cno from course where tno in (select tno from teacher where depart='计算机系' ))
-- 方法二
select sc.*
from score sc ,teacher t ,course c
where t.tno =c.tno and c.cno = sc.cno and t.depart='计算机系'
