student 数据库表练习（高级查询）

数据库表下载链接：

https://download.csdn.net/download/weixin_46098676/21185167

练习：

-- 1、 查询Student表中的所有记录的Sname、Ssex和Class列。
select sname,ssex,class from student;
-- 2、 查询教师所有的单位即不重复的Depart列。
select distinct depart from teacher;
-- 3、 查询Student表的所有记录。
select * from student;
-- 4、 查询Score表中成绩在60到80之间的所有记录。
select degree from score where degree between 60 and 80;
-- 5、 查询Score表中成绩为85，86或88的记录。
select degree from score where degree in ('85','86','88');
-- 6、 查询Student表中“95031”班或性别为“女”的同学记录。
select * from student where class='95031' or ssex='女';
-- 7、 以Class降序查询Student表的所有记录。
select  * from student order by class desc ;
-- 8、 以Cno升序、Degree降序查询Score表的所有记录。
select  * from score order by  cno asc;
select * from score order by  degree desc;
-- 9、 查询“95031”班的学生人数。
select count(*) from student where class='95031';
-- 10、查询Score表中的最高分的学生学号和课程号。（子查询或者排序）
select * from score;
select sno,cno from score order by degree desc limit 1; -- 103 3-105 (排序)
select sno,cno from score where degree = (select max(degree) from score); -- 103 3-105 (子查询)
-- 11、查询每门课的平均成绩。
select cno,avg(degree) from score group by cno;
-- 12、查询Score表中至少有5名学生选修的并以3开头的课程的平均分数。
select round(avg(degree),1)  平均成绩 from score where cno like '3%' having count(*)>5;
-- 13、查询分数大于70，小于90的Sno列。
select cno from score where degree between 70 and 90;
-- 14、查询所有学生的Sname、Cno和Degree列。
select  sname,cno,degree from score
         left join student on student.sno=score.sno;
-- 15、查询所有学生的Sno、Cname和Degree列。
select sno,cname,degree from score
       left join course c on score.cno = c.cno;
-- 16、查询所有学生的Sname、Cname和Degree列。
select sname,cname,degree from score sc , student stu ,course c where sc.cno=c.cno and stu.sno=sc.sno;
-- 17、查询“95033”班学生的平均分。
select round(avg(degree),1)  from score where sno in (select sno from student where class='95033');
-- 18、现查询所有同学的Sno、Cno和rank列。
create table grade('low'  int(3),'upp'  int(3), 'rank' char(1));
insert into grade values(90,100,'A');
insert into grade values(80,89,'B');
insert into grade values(70,79,'C');
insert into grade values(60,69,'D');
insert into grade values(0,59,'E');
select sno,cno,'rank' from score sc, grade g
where sc.degree between g.low and g.upp;
-- 19、查询选修“3-105”课程的成绩高于“109”号同学成绩的所有同学的记录。
select cno,degree from score where sno='109';
select * from score where cno='3-105' and degree>(select degree from score where sno='109' and cno='3-105');
-- 20、查询选了多门课程并且是这个课程下不是最高分的学员信息
select * from score where sno in (select sno from score group by sno having count(*)>1) and  degree <(select max(degree) from score);
-- 21、查询成绩高于学号为“109”、课程号为“3-105”的成绩的所有记录。
select * from score where degree>(select degree from score where sno='109' and cno='3-105');
-- 22、查询和学号为108、101的同学同年出生的所有学生的Sno、Sname和Sbirthday列。
select  sno, sname, sbirthday from student where year(sbirthday)=(select year(sbirthday) from student where sno ='101');
select  sno, sname, sbirthday from student where year(sbirthday)=(select year(sbirthday) from student where sno ='108');
-- 23、查询“张旭“教师任课的学生成绩。
select  * from score where cno = (select cno from teacher where tname='张旭');
-- 24、查询选修某课程的同学人数多于5人的教师姓名。
select * from teacher;
select * from score;
select tname from teacher where  tno in(select tno from course where cno in(select cno from score group by cno having count(*)>5));
-- 25、查询95033班和95031班全体学生的记录。
select * from student where class='95033' or class= '95031';
-- 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 teacher where depart='计算机系');
-- 28、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 where prof not in(select prof from teacher where depart='计算机系' and prof in(select prof from teacher where depart='电子工程系'));
-- 29、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。
-- any:代表括号中任意一个成绩就可以
select cno,sno, degree from score  where cno='3-105' and
  degree>any(select degree from score where cno='3-245')
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.
-- all:代表括号中的所有成绩
select cno,sno, degree from score  where cno='3-105' and
  degree>all(select degree from score where cno='3-245');
-- 31、查询所有教师和同学的name、sex和birthday.
select tname,tsex,tbirthday from teacher union
select sname,ssex,sbirthday from student;
-- 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 a where
    degree<(select avg(degree) from score b  where b.cno=a.cno group by cno );
-- 34、查询所有任课教师的Tname和Depart.
select tname,depart from teacher t,course c where c.tno=t.tno and  c.cno  in (select cno from score);
-- 35、查询所有未讲课的教师的Tname和Depart.
select * from teacher;
select tname,depart from teacher t,course c where c.tno=t.tno and  c.cno not in (select cno from score);
-- 36、查询至少有2名男生的班号。
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%';
-- 38、查询Student表中每个学生的姓名和年龄。
select sname,year(now())-year(sbirthday) 年龄 from student;
-- 39、查询Student表中最大和最小的Sbirthday日期值。
select  max(sbirthday) 最大的,min(sbirthday) 最小的  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 desc ;
-- 41、查询“男”教师及其所上的课程。
select * from teacher t,course c where t.tno=c.tno and t.tsex='男';
-- 42、查询最高分同学的Sno、Cno和Degree列。
select * from score where degree=(select max(degree) from score);

-- 排序写法：
-- 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');
-- 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');
-- 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');