mysql数据库表的查询
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一、 设有一数据库，包括四个表：学生表（Student）、课程表（Course）、成绩表（Score）以及教师信息表（Teacher）。四个表的结构分别如表1-1的表（一）~表（四）所示，数据如表1-2的表（一）~表（四）所示。用SQL语句创建四个表并完成相关题目。
表1-1数据库的表结构
表（一）Student (学生use)
|
属性名 |
数据类型 |
可否为空 |
含 义 |
|
Sno |
varchar (20) |
否 |
学号（主码） |
|
Sname |
varchar (20) |
否 |
学生姓名 |
|
Ssex |
varchar (20) |
否 |
学生性别 |
|
Sbirthday |
Datetime |
可 |
学生出生年月 |
|
Class |
varchar (20) |
可 |
学生所在班级 |
表（二）Course（课程表）
|
属性名 |
数据类型 |
可否为空 |
含 义 |
|
Cno |
varchar (20) |
否 |
课程号（主码） |
|
Cname |
varchar (20) |
否 |
课程名称 |
|
Tno |
varchar (20) |
否 |
教工编号 |
表（三）Score(成绩表)
|
属性名 |
数据类型 |
可否为空 |
含 义 |
|
Id |
Int |
|
主键 自增 |
|
Sno |
varchar (20) |
否 |
学号 |
|
Cno |
varchar (20) |
否 |
课程号 |
|
Degree |
Decimal(4,1)
|
可 |
成绩 |
|
//主码：Sno+ Cno |
|||
表（四）Teacher(教师表)
|
属性名 |
数据类型 |
可否为空 |
含 义 |
|
Tno |
varchar (20) |
否 |
教工编号（主码） |
|
Tname |
varchar (20) |
否 |
教工姓名 |
|
Tsex |
varchar (20) |
否 |
教工性别 |
|
Tbirthday |
datetime |
可 |
教工出生年月 |
|
Prof |
varchar (20) |
可 |
职称 |
|
Depart |
varchar (20) |
否 |
教工所在部门 |
表1-2数据库中的数据
表（一）Student
|
Sno |
Sname |
Ssex |
Sbirthday |
class |
|
108 |
曾华 |
男 |
1977-09-01 |
95033 |
|
105 |
匡明 |
男 |
1975-10-02 |
95031 |
|
107 |
王丽 |
女 |
1976-01-23 |
95033 |
|
101 |
李军 |
男 |
1976-02-20 |
95033 |
|
109 |
王芳 |
女 |
1975-02-10 |
95031 |
|
103 |
陆君 |
男 |
1974-06-03 |
95031 |
表（二）Course
|
Cno |
Cname |
Tno |
|
3-105 |
计算机导论 |
825 |
|
3-245 |
操作系统 |
804 |
|
6-166 |
数字电路 |
856 |
|
9-888 |
高等数学 |
831 |
表（三）Score
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 degree > 68 and cno = ‘3-105’ order by degree desc;
Select min(degree) from score where cno = ‘3-245’;
|
Sno |
Cno |
Degree |
|
103 |
3-245 |
86 |
|
105 |
3-245 |
75 |
|
109 |
3-245 |
68 |
|
103 |
3-105 |
92 |
|
105 |
3-105 |
88 |
|
109 |
3-105 |
76 |
|
101 |
3-105 |
64 |
|
107 |
3-105 |
91 |
|
108 |
3-105 |
78 |
|
101 |
6-166 |
85 |
|
107 |
6-166 |
79 |
|
108 |
6-166 |
81 |
表（四）Teacher
|
Tno |
Tname |
Tsex |
Tbirthday |
Prof |
Depart |
|
804 |
李诚 |
男 |
1958-12-02 |
副教授 |
计算机系 |
|
856 |
张旭 |
男 |
1969-03-12 |
讲师 |
电子工程系 |
|
825 |
王萍 |
女 |
1972-05-05 |
助教 |
计算机系 |
|
831 |
刘冰 |
女 |
1977-08-14 |
助教 |
电子工程系 |
包含步骤思路
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 60<degree and degree<80;
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=85 or degree=86 or degree=88;
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。升序（asc可省略）
select * from score order by cno,degree desc;
9、查询“95031”班的学生人数。
select count(sname) 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）
子查询
select max(degree) from score;
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),cno from score where cno like "3%" group by cno having count(cno)>=5;
13、查询分数大于70，小于90的Sno列。
select sno from score where degree>70 and degree<90;
14、查询所有学生的Sname、Cno和Degree列。
select sname,cno,degree from student join score on student.sno=score.sno;
15、查询所有学生的Sno、Cname和Degree列。
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 sname,cname,degree from student join score on student.sno=score.sno join course on course.cno=score.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‘);
select avg(degree) from score join student on student.sno=score.sno where class=‘95033‘;
18、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 from score where cno="3-105";
select degree from score where sno="109"and cno="3-105";
select * from score where cno in (select cno from score where cno="3-105") and degree>(select degree from score where sno="109"and cno="3-105");
select * from student join score on student.sno=score.sno where score.cno="3-105" and score.degree>(select degree from score where sno="109"and cno="3-105");
19、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 sno from score group by sno having count(cno)>1;
select max(degree) from score;
select * from score where degree<(select max(degree) from score) and sno in (select sno from score group by sno having count(cno)>1);
20、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 degree from score where sno=109 and cno="3-105";
select * from student join score on student.sno=score.sno where degree>(select degree from score where sno=109 and cno="3-105");
21、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 Sbirthday from student where sno=108;
select sno,sname,sbirthday from student where year(sbirthday)=(select year(sbirthday) from student where sno=108);
22、查询“张旭“教师任课的学生成绩（姓名）。
select tno from teacher where tname="张旭";
select cno from course where tno in (select tno from teacher where tname="张旭");
select degree from score where cno in (select cno from course where tno in (select tno from teacher where tname="张旭"));
select sname,degree from student join score on student.sno=score.sno join course on course.cno=score.cno join teacher on teacher.tno=course.tno where teacher.tname="张旭";
23、查询考计算机导论的学生成绩
select cno from course where cname like "计算机导论";
select sno,degree from score where cno in (select cno from course where cname like "计算机导论");
24、查询 所有的列/字段 从 成绩表(score) 条件是
select * from score;
25、课程名(cname)称为计算机导论 的课程编号
select cno from course where cname="计算机导论";
26、查询李诚老师教的课程名称
select tno from teacher where tname="李诚";
select cname from course where tno in (select tno from teacher where tname="李诚");
27、教高等数学的老师是哪个系的
select tno from course where cname="高等数学";
select depart from teacher where tno=(select tno from course where cname="高等数学");
28、查询选修某课程的同学人数多于5人的教师姓名。
select cno from score group by cno having count(sno)>5;
select tno from course where cno=(select cno from score group by cno having count(sno)>5);
select tname from teacher where tno=(select tno from course where cno=(select cno from score group by cno having count(sno)>5));
29、查询95033班和95031班全体学生的记录。
select sno from student where class="95033" or class="95031";
select * from student join score on student.sno=score.sno where student.sno in (select sno from student where class="95033" or class="95031");
30、查询成绩表中存在有85分以上成绩的课程Cno.
select distinct cno from score where degree>85;
31、查询出“计算机系“教师所教课程的成绩表。
select tno from teacher where depart="计算机系";
select cno from course where tno in (select tno from teacher where depart="计算机系");
select cno,degree from score where cno in (select cno from course where tno in (select tno from teacher where depart="计算机系"));
32、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 cno,sno,degree from score where cno="3-105" and degree>(select max(degree) from score where cno="3-245");
33、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;
34、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";
35、查询所有成绩比3-105课程平均成绩低的同学的成绩表。
select avg(degree) from score where cno="3-105";
select * from score where degree<(select avg(degree) from score where cno="3-105");
36、查询所有任课教师的Tname和Depart.
select distinct cno from score;
select tno from course where cno in (select distinct cno from score);
select tname,depart from teacher where tno in (select tno from course where cno in (select distinct cno from score));
37、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 distinct cno from score));
38、查询至少有2名男生的班号。
select class from student group by class having count(ssex)>=2;
39、查询Student表中不姓“王”的同学记录。
select * from student where sname not like "王%";
40、查询Student表中每个学生的姓名和年龄。
select sname,year(now()) - year(sbirthday) as 年龄 from student;
41、查询Student表中最大和最小的Sbirthday日期值。
select min(sbirthday) as 最大,max(sbirthday) as 最小 from student;
42、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;
43、查询“男”教师及其所上的课程。
select * from teacher where tsex="男";
select tno from teacher where tsex="男";
select cname from course where tno in (select tno from teacher where tsex="男");
select tname,cname from teacher join course on teacher.tno=course.tno where tsex="男";
44、查询最高分同学的Sno、Cno和Degree列。
select max(degree) from score;
select sno,cno,degree from score where degree=(select max(degree) from score);
45、查询和“李军”同性别的所有同学的Sname.
select ssex from student where sname="李军";
select sname from student where ssex in (select ssex from student where sname="李军");
46、查询和“李军”同性别并同班的同学Sname.
select class from student where sname="李军";
select sname from student where ssex in (select ssex from student where sname="李军") and class in (select class from student where sname="李军");
47、查询所有选修“计算机导论”课程的“男”同学的成绩表。
select cno from course where cname="计算机导论";
select sno from student where ssex="男";
select * from score where cno in (select cno from course where cname="计算机导论") and sno in(select sno from student where ssex="男");
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