建表 create table Student ( Sno varchar(20) not null primary key, Sname varchar(20) not null, Ssex varchar(20) not null, Sbirthday datetime, Class varchar(20) ) create table Course ( Cno varchar(20) not null primary key , Cname varchar(20) not null, Tno varchar(20) not null, foreign key (Tno) references Teacher (Tno) ); create table Teacher ( Tno varchar(20) not null primary key, Tname varchar(20) not null, Tsex varchar(20) not null, Tbirthday datetime, Prof varchar(20), Depart varchar(20) not null ) create table Score ( Sno varchar(20) not null , Cno varchar(20) not null, Degree Decimal(4,1), primary key(Sno,Cno),#建两个主键叫联合主键 foreign key (Sno) references Student(Sno),#这样建外键才有效 foreign key (Cno) references Course (Cno) ) 录入信息 insert into Student values('108','曾华','男','1977-09-01','95033') insert into Student values('105','匡明','男','1975-10-02','95031') insert into Student values('107', '王丽','女','1976-01-023','95033'),( '101','李军','男','1976-02-20','95033') insert into Student values('109', '王芳','女','1975-02-10','95031') insert into Student values( '103','陆君','男','1974-06-03','95031') insert into Course values('3-105','计算机导论','825') insert into Course values('3-245','操作系统','804') insert into Course values('6-166','数字电路','856') insert into Course values('9-888','高等数学','831') insert into Teacher values('804','李诚','男','1958-12-02','副教授','计算机系') insert into Teacher values('856','张旭','男','1969-03-12','讲师','电子工程系') insert into Teacher values('825','王萍','女','1972-05-05','助教','计算机系') insert into Teacher values('831','刘冰','女','1977-08-14','助教','电子工程系') insert into Score values('103','3-245','86') insert into Score values('105','3-245','75') insert into Score values('109','3-245','68') insert into Score values('103','3-105','92') insert into Score values('105','3-105','88') insert into Score values ('109','3-105','76') insert into Score values ('101','3-105','64') insert into Score values ('107','3-105','91') insert into Score values('108','3-105','78'); insert into Score values('101','6-166','85'); insert into Score values('107','6-166','79'); insert into Score values('108','6-166','81') #填入信息时一定按主从表的顺序建要不添加不上，要想建外键也是先建主表在建从表 查询Student表中的所有记录的Sname、Ssex和Class列。 1.select Sname,Ssex,Class from Student 查询教师所有的单位即不重复的Depart列。 2.select distinct Depart from Teacher#去重 查询Student表的所有记录。 3.select *from Student 查询Score表中成绩在60到80之间的所有记录 4.select*from Score where Degree between '60 'and '80' select*from Score where Degree >'60' and Degree<'80'# 不用加单引号 查询Score表中成绩为85，86或88的记录。 5.select*from Score where Degree='85'and Degree='86'or Degree='88' select*from Score where Degree in(85,86,88) 查询Student表中“95031”班或性别为“女”的同学记录。 6.select *from Student where Class='95031'or Ssex='女' 以Class降序查询Student表的所有记录。 7.select*from Student order by Class desc 以Cno升序、Degree降序查询Score表的所有记录。 8.select*from Score order by Cno asc, Degree desc 查询“95031”班的学生人数。 9.select count(*) from Student where class='95031' 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） 10.select Sno,Cno from Score where Degree= ( select max(Degree) from Score ) 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 avg (Degree)from Score group by Cno having count(*)>5 and Cno like '3%' select avg(Degree) from Score where Cno in (select Cno from Score group by Cno having count(*)>5) and Cno like '3%' group by Cno 13、查询分数大于70，小于90的Sno列。 select Sno from Score WHERE Degree>'70 'and Degree<'90' select sno from score where Degree between '70'and '90' 14、查询所有学生的Sname、Cno和Degree列。 select Student.Sname,Score.Cno, Score.Degree from Student,Score select Sname,Cno,Degree from Score join Student on Student.Sno = Score.Sno 15、查询所有学生的Sno、Cname和Degree列。 select Student.Sno,Cname,Degree from Student, Course,Score where Student.Sno=Score.sno select Student.Sno, Course.Cname,Score.Degree from Student,Course,Score select Sno,Cname,Degree from Score join Course on Score.Cno = Course.Cno 16、查询所有学生的Sname、Cname和Degree列。 select Student.Sname,Course.Cname,Score.Degree from Student,Course,Score where Student.Sno=Score.Sno and Course.Cno=Score.Cno select Sname,Cname,Degree from Score join Student on Student.Sno = Score.Sno join Course on Score.Cno = Course.Cno 17、 查询“95033"班学生的平均分。 select avg (Degree) from Score where Sno in (select Sno from Student where Class='95033') 18、 假设使用如下命令建立了一个grade表： 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’); 现查询所有同学的Sno、Cno和rank列。 select Sno,cno,rank from Score join grade on Score.Degree between low and 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 *from score where cno ='3-105' and degree>(select degree from score where cno='3-105'and Sno='109') 20、查询score中选学多门课程的同学中分数为非最高分成绩的记录。 select*from score a where Sno in (select sno from Score group by Sno having count(*)>1)and Degree not in ( select max (Degree)from Score b where b.Cno=a.Cno)#第一种理解 选多门课程的同学指一个同学选好几门 用到相关子查询 第二种理解 选多门课程的同学指多个同学从多门课程中选 select * from Score a where Sno in (select Sno from Score group by Sno having count(*)>1 ) and Degree not in (select max(Degree) from Score a where Sno in (select Sno from Score group by Sno having count(*)>1 )) 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的同学同年出生的所有学生的Sno、Sname和Sbirthday列。 select student.Sno, student.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 Tname,Sname,degree from teacher, course,score, student where student.sno =score.sno and teacher.Tno=course.Tno and course.cno=score.cno and teacher.Tname='张旭' select*from Score where cno in (select cno from course where tno=( select Tno from Teacher wherer 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 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 in ('95031','95033') 26、 查询存在有85分以上成绩的课程Cno. select distinc 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 Course where Tno in (select Tno from Teacher where 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。 select*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. select*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 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 a where Degree<(select avg (Degree) from Score b where b.Cno=a.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) 成绩表上：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 in(select Tno from Course where 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 Sno not in (select Sno from Student where Sname like'王%') 38、查询Student表中每个学生的姓名和年龄。 select Sname,YEAR (now())-year(Sbirthday) from Student 39、查询Student表中最大和最小的Sbirthday日期值。 select max(Sbirthday)from Student union select min(Sbirthday) from Student #这样写运行只有一个最大值得表拦 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 desc 41、查询“男”教师及其所上的课程。 select*from Teacher join Course on Teacher.Tno=Course.Tno where Teacher.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) 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 Sno in (select Sno from Student where Ssex='男')and Cno in(select Cno from Course where Cname='计算机导论')