sql查询练习

作者: 夜空最亮的9星 | 来源:发表于2018-06-12 18:18 被阅读55次

sql 练习(三)
SQL练习
sql查询练习
SQL查询练习
sql 练习(二)
sql查询练习2
sql 查询语句练习
51 SQL 复习语句关系代数（二）
EF Core 备忘
sqli_labs 练习笔记

建表语句：

CREATE TABLE students
(sno VARCHAR(3) NOT NULL, 
sname VARCHAR(4) NOT NULL,
ssex VARCHAR(2) NOT NULL, 
sbirthday DATETIME,
class VARCHAR(5));

CREATE TABLE courses
(cno VARCHAR(5) NOT NULL, 
cname VARCHAR(10) NOT NULL, 
tno VARCHAR(10) NOT NULL);



CREATE TABLE scores 
(sno VARCHAR(3) NOT NULL, 
cno VARCHAR(5) NOT NULL, 
degree NUMERIC(10, 1) NOT NULL);

CREATE TABLE teachers 
(tno VARCHAR(3) NOT NULL, 
tname VARCHAR(4) NOT NULL, tsex VARCHAR(2) NOT NULL, 
tbirthday DATETIME NOT NULL, prof VARCHAR(6), 
depart VARCHAR(10) NOT NULL);

准备数据：

INSERT INTO STUDENTS (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (108 ,'曾华' ,'男' ,'1977-09-01',95033);
INSERT INTO STUDENTS (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (105 ,'匡明' ,'男' ,'1975-10-02',95031);
INSERT INTO STUDENTS (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (107 ,'王丽' ,'女' ,'1976-01-23',95033);
INSERT INTO STUDENTS (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (101 ,'李军' ,'男' ,'1976-02-20',95033);
INSERT INTO STUDENTS (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (109 ,'王芳' ,'女' ,'1975-02-10',95031);
INSERT INTO STUDENTS (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (103 ,'陆君' ,'男' ,'1974-06-03',95031);

INSERT INTO COURSES(CNO,CNAME,TNO)VALUES ('3-105' ,'计算机导论',825);
INSERT INTO COURSES(CNO,CNAME,TNO)VALUES ('3-245' ,'操作系统' ,804);
INSERT INTO COURSES(CNO,CNAME,TNO)VALUES ('6-166' ,'数据电路' ,856);
INSERT INTO COURSES(CNO,CNAME,TNO)VALUES ('9-888' ,'高等数学' ,100);

INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (103,'3-245',86);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (105,'3-245',75);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (109,'3-245',68);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (103,'3-105',92);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (105,'3-105',88);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (109,'3-105',76);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (101,'3-105',64);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (107,'3-105',91);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (108,'3-105',78);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (101,'6-166',85);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (107,'6-106',79);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (108,'6-166',81);

INSERT INTO TEACHERS(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) VALUES (804,'李诚','男','1958-12-02','副教授','计算机系');
INSERT INTO TEACHERS(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) VALUES (856,'张旭','男','1969-03-12','讲师','电子工程系');
INSERT INTO TEACHERS(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) VALUES (825,'王萍','女','1972-05-05','助教','计算机系');
INSERT INTO TEACHERS(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) VALUES (831,'刘冰','女','1977-08-14','助教','电子工程系');

mysql> show tables;
+-------------------+
| Tables_in_db_demo |
+-------------------+
| courses           |
| scores            |
| students          |
| teachers          |
+-------------------+
4 rows in set (0.00 sec)

题目：
1、查询Student表中的所有记录的Sname、Ssex和Class列。

mysql> select distinct Sname,Ssex,Class from students;
+--------+------+-------+
| Sname  | Ssex | Class |
+--------+------+-------+
| 曾华   | 男   | 95033 |
| 匡明   | 男   | 95031 |
| 王丽   | 女   | 95033 |
| 李军   | 男   | 95033 |
| 王芳   | 女   | 95031 |
| 陆君   | 男   | 95031 |
+--------+------+-------+
6 rows in set (0.00 sec)

2、查询教师所有的单位即不重复的Depart列。

mysql> select distinct depart from teachers;
+-----------------+
| depart          |
+-----------------+
| 计算机系        |
| 电子工程系      |
+-----------------+
2 rows in set (0.00 sec)

3、查询Student表的所有记录。

mysql> select * from students;
+-----+--------+------+---------------------+-------+
| sno | sname  | ssex | sbirthday           | class |
+-----+--------+------+---------------------+-------+
| 108 | 曾华   | 男   | 1977-09-01 00:00:00 | 95033 |
| 105 | 匡明   | 男   | 1975-10-02 00:00:00 | 95031 |
| 107 | 王丽   | 女   | 1976-01-23 00:00:00 | 95033 |
| 101 | 李军   | 男   | 1976-02-20 00:00:00 | 95033 |
| 109 | 王芳   | 女   | 1975-02-10 00:00:00 | 95031 |
| 103 | 陆君   | 男   | 1974-06-03 00:00:00 | 95031 |
| 108 | 曾华   | 男   | 1977-09-01 00:00:00 | 95033 |
| 105 | 匡明   | 男   | 1975-10-02 00:00:00 | 95031 |
| 107 | 王丽   | 女   | 1976-01-23 00:00:00 | 95033 |
| 101 | 李军   | 男   | 1976-02-20 00:00:00 | 95033 |
| 109 | 王芳   | 女   | 1975-02-10 00:00:00 | 95031 |
| 103 | 陆君   | 男   | 1974-06-03 00:00:00 | 95031 |
+-----+--------+------+---------------------+-------+
12 rows in set (0.00 sec)

4、查询Score表中成绩在60到80之间的所有记录。

mysql> select * from scores where degree between 60 and  80;
+-----+-------+--------+
| sno | cno   | degree |
+-----+-------+--------+
| 105 | 3-245 |   75.0 |
| 109 | 3-245 |   68.0 |
| 109 | 3-105 |   76.0 |
| 101 | 3-105 |   64.0 |
| 108 | 3-105 |   78.0 |
| 107 | 6-106 |   79.0 |
+-----+-------+--------+
6 rows in set (0.01 sec)

5、查询Score表中成绩为85，86或88的记录。

mysql> select * from scores where degree in (85,86,88);
+-----+-------+--------+
| sno | cno   | degree |
+-----+-------+--------+
| 103 | 3-245 |   86.0 |
| 103 | 3-245 |   86.0 |
| 105 | 3-105 |   88.0 |
| 101 | 6-166 |   85.0 |
+-----+-------+--------+
4 rows in set (0.00 sec)

6、查询Student表中“95031”班或性别为“女”的同学记录。

mysql> select sname,ssex,class from students where class = '95031'  or ssex ='女' group by sname;
+--------+------+-------+
| sname  | ssex | Class |
+--------+------+-------+
| 匡明   | 男   | 95031 |
| 王丽   | 女   | 95033 |
| 王芳   | 女   | 95031 |
| 陆君   | 男   | 95031 |
+--------+------+-------+
4 rows in set (0.00 sec)

7、以Class降序查询Student表的所有记录。

mysql> select sno,sname ,class from students group by sno order by class desc;
+-----+--------+-------+
| sno | sname  | class |
+-----+--------+-------+
| 108 | 曾华   | 95033 |
| 107 | 王丽   | 95033 |
| 101 | 李军   | 95033 |
| 103 | 陆君   | 95031 |
| 105 | 匡明   | 95031 |
| 109 | 王芳   | 95031 |
+-----+--------+-------+
6 rows in set (0.00 sec)

8、以Cno升序、Degree降序查询Score表的所有记录。

mysql> select cno,degree from scores order by cno,degree desc;
+-------+--------+
| cno   | degree |
+-------+--------+
| 3-105 |   92.0 |
| 3-105 |   91.0 |
| 3-105 |   88.0 |
| 3-105 |   78.0 |
| 3-105 |   76.0 |
| 3-105 |   64.0 |
| 3-245 |   86.0 |
| 3-245 |   86.0 |
| 3-245 |   75.0 |
| 3-245 |   68.0 |
| 6-106 |   79.0 |
| 6-166 |   85.0 |
| 6-166 |   81.0 |
+-------+--------+
13 rows in set (0.00 sec)

9、查询“95031”班的学生人数。


mysql> select count(*) from students where class = 95031;
+----------+
| count(*) |
+----------+
|        6 |
+----------+
1 row in set (0.00 sec)

10、查询Score表中的最高分的
学生学号和课程号。

mysql> select max(degree) from scores;
+-------------+
| max(degree) |
+-------------+
|        92.0 |
+-------------+
1 row in set (0.00 sec)

mysql> select * from scores where degree = (select max(degree) from scores);
+-----+-------+--------+
| sno | cno   | degree |
+-----+-------+--------+
| 103 | 3-105 |   92.0 |
+-----+-------+--------+
1 row in set (0.00 sec)

mysql>

11、查询‘3-105’号课程的平均分。

mysql> select avg(DEGREE) from SCORES  where cno = '3-105';
+-------------+
| avg(DEGREE) |
+-------------+
|    81.50000 |
+-------------+
1 row in set (0.00 sec)

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。

mysql> select cno ,avg(degree) from scores where cno like '3%' group by cno having count(1)>5;
+-------+-------------+
| cno   | avg(degree) |
+-------+-------------+
| 3-105 |    81.50000 |
+-------+-------------+
1 row in set (0.00 sec)

13、查询最低分大于70，最高分小于90的Sno列。

mysql> select sc.sno from scores sc,students st where st.sno=sc.sno group by sc.sno having min(sc.degree)>70 and max(sc.degree)<90;
+-----+
| sno |
+-----+
| 105 |
| 108 |
+-----+
2 rows in set (0.00 sec)

14、查询所有学生的Sname、Cno和Degree列。

mysql>  select sname,cno,degree from students as std left join scores sc on std.sno = sc.sno group by sname;
+--------+-------+--------+
| sname  | cno   | degree |
+--------+-------+--------+
| 匡明   | 3-245 |   75.0 |
| 曾华   | 3-105 |   78.0 |
| 李军   | 3-105 |   64.0 |
| 王丽   | 3-105 |   91.0 |
| 王芳   | 3-245 |   68.0 |
| 陆君   | 3-245 |   86.0 |
+--------+-------+--------+
6 rows in set (0.00 sec)

15、查询所有学生的Sno、Cname和Degree列。

mysql> select students.sno,courses.cname ,scores.degree from students ,courses,scores where students.sno =  scores.sno and courses.cno = scores.cno group by students.sno;
+-----+-----------------+--------+
| sno | cname           | degree |
+-----+-----------------+--------+
| 101 | 计算机导论      |   64.0 |
| 103 | 操作系统        |   86.0 |
| 105 | 操作系统        |   75.0 |
| 107 | 计算机导论      |   91.0 |
| 108 | 计算机导论      |   78.0 |
| 109 | 操作系统        |   68.0 |
+-----+-----------------+--------+
6 rows in set (0.00 sec)

16、查询所有学生的Sname、Cname和Degree列。

mysql> select students.sname,courses.cname ,scores.degree from students ,courses,scores where students.sno =  scores.sno and courses.cno = scores.cno group by students.sno;
+--------+-----------------+--------+
| sname  | cname           | degree |
+--------+-----------------+--------+
| 李军   | 计算机导论      |   64.0 |
| 陆君   | 操作系统        |   86.0 |
| 匡明   | 操作系统        |   75.0 |
| 王丽   | 计算机导论      |   91.0 |
| 曾华   | 计算机导论      |   78.0 |
| 王芳   | 操作系统        |   68.0 |
+--------+-----------------+--------+
6 rows in set (0.00 sec)

17、查询“95033”班所选课程的平均分。

mysql> select cr.cno,cr.cname,avg(sc.degree) from courses cr,scores sc,students st where  st.sno=sc.sno and st.class='95033' and sc.cno=cr.cno group by cr.cno,cr.cname;
+-------+-----------------+----------------+
| cno   | cname           | avg(sc.degree) |
+-------+-----------------+----------------+
| 3-105 | 计算机导论      |       77.66667 |
| 6-166 | 数据电路        |       83.00000 |
+-------+-----------------+----------------+
2 rows in set (0.00 sec)

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');
commit;

现查询所有同学的Sno、Cno和rank列。


select sno from scores inner join students on scores.sno = students.sno;

select * from students inner join grade where students.

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。

mysql> select  distinct st.sno,st.sname,sc.degree from students st,scores sc where sc.cno='3-105' and sc.degree> (select degree from scores where cno='3-105'and sno='109') and st.sno=sc.sno;;
+-----+--------+--------+
| sno | sname  | degree |
+-----+--------+--------+
| 108 | 曾华   |   78.0 |
| 105 | 匡明   |   88.0 |
| 107 | 王丽   |   91.0 |
| 103 | 陆君   |   92.0 |
+-----+--------+--------+
4 rows in set (0.00 sec)

20、查询score中选学一门以上课程的同学中分数为非最高分成绩的记录。

mysql> select * from scores where degree < (select max(degree) from scores) having count(*) >1;
+-----+-------+--------+
| sno | cno   | degree |
+-----+-------+--------+
| 103 | 3-245 |   86.0 |
+-----+-------+--------+
1 row in set (0.00 sec)

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。

mysql> select distinct * from scores where degree > all (select degree from scores where sno = '109' and cno = '3-105');
+-----+-------+--------+
| sno | cno   | degree |
+-----+-------+--------+
| 103 | 3-245 |   86.0 |
| 103 | 3-105 |   92.0 |
| 105 | 3-105 |   88.0 |
| 107 | 3-105 |   91.0 |
| 108 | 3-105 |   78.0 |
| 101 | 6-166 |   85.0 |
| 107 | 6-106 |   79.0 |
| 108 | 6-166 |   81.0 |
+-----+-------+--------+
8 rows in set (0.00 sec)

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。

mysql> select distinct sno,sname ,sbirthday from students where sbirthday = (select distinct sbirthday from students where sno = 108);
+-----+--------+---------------------+
| sno | sname  | sbirthday           |
+-----+--------+---------------------+
| 108 | 曾华   | 1977-09-01 00:00:00 |
+-----+--------+---------------------+
1 row in set (0.00 sec)

23、查询“张旭“教师任课的学生成绩。

mysql> select distinct * from scores  where cno = (select distinct cno from  courses inner join teachers  where  teachers.tno = courses.tno and teachers.tname = '张旭');
+-----+-------+--------+
| sno | cno   | degree |
+-----+-------+--------+
| 101 | 6-166 |   85.0 |
| 108 | 6-166 |   81.0 |
+-----+-------+--------+
2 rows in set (0.00 sec)

24、查询选修某课程的同学人数多于5人的教师姓名。

mysql> select tname from teachers where tno in (select tno from courses where cno in (select cno from scores group by cno having COUNT(*)>5));
+--------+
| tname  |
+--------+
| 王萍   |
+--------+
1 row in set (0.00 sec)

25、查询95033班和95031班全体学生的记录。

mysql> select * from students where class = '95033' or class = '95031';
+-----+--------+------+---------------------+-------+
| sno | sname  | ssex | sbirthday           | class |
+-----+--------+------+---------------------+-------+
| 108 | 曾华   | 男   | 1977-09-01 00:00:00 | 95033 |
| 105 | 匡明   | 男   | 1975-10-02 00:00:00 | 95031 |
| 107 | 王丽   | 女   | 1976-01-23 00:00:00 | 95033 |
| 101 | 李军   | 男   | 1976-02-20 00:00:00 | 95033 |
| 109 | 王芳   | 女   | 1975-02-10 00:00:00 | 95031 |
| 103 | 陆君   | 男   | 1974-06-03 00:00:00 | 95031 |
| 108 | 曾华   | 男   | 1977-09-01 00:00:00 | 95033 |
| 105 | 匡明   | 男   | 1975-10-02 00:00:00 | 95031 |
| 107 | 王丽   | 女   | 1976-01-23 00:00:00 | 95033 |
| 101 | 李军   | 男   | 1976-02-20 00:00:00 | 95033 |
| 109 | 王芳   | 女   | 1975-02-10 00:00:00 | 95031 |
| 103 | 陆君   | 男   | 1974-06-03 00:00:00 | 95031 |
+-----+--------+------+---------------------+-------+
12 rows in set (0.00 sec)

26、查询存在有85分以上成绩的课程Cno.

mysql> select cno from scores where degree > 85;
+-------+
| cno   |
+-------+
| 3-245 |
| 3-245 |
| 3-105 |
| 3-105 |
| 3-105 |
+-------+
5 rows in set (0.00 sec)

27、查询出“计算机系“教师所教课程的成绩表。

mysql> select * from scores where cno in (select cno from courses where tno in (select tno from teachers where depart='计算机系'));
+-----+-------+--------+
| sno | cno   | degree |
+-----+-------+--------+
| 103 | 3-245 |   86.0 |
| 103 | 3-245 |   86.0 |
| 105 | 3-245 |   75.0 |
| 109 | 3-245 |   68.0 |
| 103 | 3-105 |   92.0 |
| 105 | 3-105 |   88.0 |
| 109 | 3-105 |   76.0 |
| 101 | 3-105 |   64.0 |
| 107 | 3-105 |   91.0 |
| 108 | 3-105 |   78.0 |
+-----+-------+--------+
10 rows in set (0.00 sec)

28、查询“计算机系”与“电子工程系“不同职称的教师的Tname和Prof。

mysql> select * from teachers where depart = '计算机系' or depart = '电子工程系' group by prof ,tname;
+-----+--------+------+---------------------+-----------+-----------------+
| tno | tname  | tsex | tbirthday           | prof      | depart          |
+-----+--------+------+---------------------+-----------+-----------------+
| 804 | 李诚   | 男   | 1958-12-02 00:00:00 | 副教授    | 计算机系        |
| 831 | 刘冰   | 女   | 1977-08-14 00:00:00 | 助教      | 电子工程系      |
| 825 | 王萍   | 女   | 1972-05-05 00:00:00 | 助教      | 计算机系        |
| 856 | 张旭   | 男   | 1969-03-12 00:00:00 | 讲师      | 电子工程系      |
+-----+--------+------+---------------------+-----------+-----------------+
4 rows in set (0.00 sec)

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。

mysql> select * from scores where cno='3-105' and degree > all (select degree  from scores where cno='3-245') order by degree desc;
+-----+-------+--------+
| sno | cno   | degree |
+-----+-------+--------+
| 103 | 3-105 |   92.0 |
| 107 | 3-105 |   91.0 |
| 105 | 3-105 |   88.0 |
+-----+-------+--------+
3 rows in set (0.00 sec)

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.

mysql> select * from scores where cno='3-105' and degree > all (select degree from scores where cno='3-245');
+-----+-------+--------+
| sno | cno   | degree |
+-----+-------+--------+
| 103 | 3-105 |   92.0 |
| 105 | 3-105 |   88.0 |
| 107 | 3-105 |   91.0 |
+-----+-------+--------+
3 rows in set (0.00 sec)

31、查询所有教师和同学的name、sex和birthday.

mysql> select distinct sname as name ,ssex as sex ,sbirthday as birthday from students union select distinct tname as name ,tsex as sex ,tbirthday as birthday from teachers ;
+--------+-----+---------------------+
| name   | sex | birthday            |
+--------+-----+---------------------+
| 曾华   | 男  | 1977-09-01 00:00:00 |
| 匡明   | 男  | 1975-10-02 00:00:00 |
| 王丽   | 女  | 1976-01-23 00:00:00 |
| 李军   | 男  | 1976-02-20 00:00:00 |
| 王芳   | 女  | 1975-02-10 00:00:00 |
| 陆君   | 男  | 1974-06-03 00:00:00 |
| 李诚   | 男  | 1958-12-02 00:00:00 |
| 张旭   | 男  | 1969-03-12 00:00:00 |
| 王萍   | 女  | 1972-05-05 00:00:00 |
| 刘冰   | 女  | 1977-08-14 00:00:00 |
+--------+-----+---------------------+
10 rows in set (0.00 sec)

32、查询所有“女”教师和“女”同学的name、sex和birthday.

mysql> select distinct sname as name,ssex as sex,sbirthday as birthday from students where ssex='女' union select distinct tname as name,tsex as sex,tbirthday as birthday from teachers where tsex='女';
+--------+-----+---------------------+
| name   | sex | birthday            |
+--------+-----+---------------------+
| 王丽   | 女  | 1976-01-23 00:00:00 |
| 王芳   | 女  | 1975-02-10 00:00:00 |
| 王萍   | 女  | 1972-05-05 00:00:00 |
| 刘冰   | 女  | 1977-08-14 00:00:00 |
+--------+-----+---------------------+
4 rows in set (0.00 sec)

33、查询成绩比该课程平均成绩低的同学的成绩表。

mysql> select * from scores sc where sc.degree between 0 and(select avg(degree) from scores sc2 where sc.cno=sc2.cno) ;
+-----+-------+--------+
| sno | cno   | degree |
+-----+-------+--------+
| 105 | 3-245 |   75.0 |
| 109 | 3-245 |   68.0 |
| 109 | 3-105 |   76.0 |
| 101 | 3-105 |   64.0 |
| 108 | 3-105 |   78.0 |
| 107 | 6-106 |   79.0 |
| 108 | 6-166 |   81.0 |
+-----+-------+--------+
7 rows in set (0.00 sec)

34、查询所有任课教师的Tname和Depart.

mysql> select tname,depart from teachers inner join courses on courses.tno = teachers.tno group by tname;
+--------+-----------------+
| tname  | depart          |
+--------+-----------------+
| 张旭   | 电子工程系      |
| 李诚   | 计算机系        |
| 王萍   | 计算机系        |
+--------+-----------------+
3 rows in set (0.00 sec)

35 查询所有未讲课的教师的Tname和Depart.

mysql> select tname,depart from teachers where tno not in  (select teachers.tno from teachers inner join courses on courses.tno = teachers.tno);
+--------+-----------------+
| tname  | depart          |
+--------+-----------------+
| 刘冰   | 电子工程系      |
+--------+-----------------+
1 row in set (0.00 sec)

36、查询至少有2名男生的班号。

mysql> select class from students where ssex = '男' group by class having count(sno)>=2;
+-------+
| class |
+-------+
| 95031 |
| 95033 |
+-------+
2 rows in set (0.00 sec)

37、查询Student表中不姓“王”的同学记录。

mysql> select * from students where sname not like '王%' group by sname;
+-----+--------+------+---------------------+-------+
| sno | sname  | ssex | sbirthday           | class |
+-----+--------+------+---------------------+-------+
| 105 | 匡明   | 男   | 1975-10-02 00:00:00 | 95031 |
| 108 | 曾华   | 男   | 1977-09-01 00:00:00 | 95033 |
| 101 | 李军   | 男   | 1976-02-20 00:00:00 | 95033 |
| 103 | 陆君   | 男   | 1974-06-03 00:00:00 | 95031 |
+-----+--------+------+---------------------+-------+
4 rows in set (0.00 sec)

38、查询Student表中每个学生的姓名和年龄。
参考

mysql> SELECT sname, ROUND(DATEDIFF(CURDATE(), sbirthday)/365.2422) as age from students group by sname;
+--------+------+
| sname  | age  |
+--------+------+
| 匡明   |   43 |
| 曾华   |   41 |
| 李军   |   42 |
| 王丽   |   42 |
| 王芳   |   43 |
| 陆君   |   44 |
+--------+------+
6 rows in set (0.00 sec)

39、查询Student表中最大和最小的sbirthday日期值。

mysql> select max(sbirthday) as maxTime ,  min(sbirthday) as minTime  from students;
+---------------------+---------------------+
| maxTime             | minTime             |
+---------------------+---------------------+
| 1977-09-01 00:00:00 | 1974-06-03 00:00:00 |
+---------------------+---------------------+
1 row in set (0.00 sec)

40、以班号和年龄从大到小的顺序查询Student表中的全部记录。

mysql> select * from students  order by class desc , sbirthday asc;
+-----+--------+------+---------------------+-------+
| sno | sname  | ssex | sbirthday           | class |
+-----+--------+------+---------------------+-------+
| 107 | 王丽   | 女   | 1976-01-23 00:00:00 | 95033 |
| 107 | 王丽   | 女   | 1976-01-23 00:00:00 | 95033 |
| 101 | 李军   | 男   | 1976-02-20 00:00:00 | 95033 |
| 101 | 李军   | 男   | 1976-02-20 00:00:00 | 95033 |
| 108 | 曾华   | 男   | 1977-09-01 00:00:00 | 95033 |
| 108 | 曾华   | 男   | 1977-09-01 00:00:00 | 95033 |
| 103 | 陆君   | 男   | 1974-06-03 00:00:00 | 95031 |
| 103 | 陆君   | 男   | 1974-06-03 00:00:00 | 95031 |
| 109 | 王芳   | 女   | 1975-02-10 00:00:00 | 95031 |
| 109 | 王芳   | 女   | 1975-02-10 00:00:00 | 95031 |
| 105 | 匡明   | 男   | 1975-10-02 00:00:00 | 95031 |
| 105 | 匡明   | 男   | 1975-10-02 00:00:00 | 95031 |
+-----+--------+------+---------------------+-------+
12 rows in set (0.00 sec)

41、查询“男”教师及其所上的课程。

mysql> select t1.tname ,cr.cname from teachers as t1  left join courses as cr on t1.tno = cr.tno  where tsex = '男' group by t1.tname ;
+--------+--------------+
| tname  | cname        |
+--------+--------------+
| 张旭   | 数据电路     |
| 李诚   | 操作系统     |
+--------+--------------+
2 rows in set (0.00 sec)

42、查询最高分同学的Sno、Cno和Degree列。

mysql> select students.sno,courses.cno,scores.degree from students , courses , scores where scores.degree = (select max(degree) from scores)  group by students.sname ;
+-----+-------+--------+
| sno | cno   | degree |
+-----+-------+--------+
| 105 | 3-105 |   92.0 |
| 108 | 3-105 |   92.0 |
| 101 | 3-105 |   92.0 |
| 107 | 3-105 |   92.0 |
| 109 | 3-105 |   92.0 |
| 103 | 3-105 |   92.0 |
+-----+-------+--------+
6 rows in set (0.00 sec)

43、查询和“李军”同性别的所有同学的Sname.

mysql> select sname from students where ssex = (select ssex from students where sname = '李军' limit 1);
+--------+
| sname  |
+--------+
| 曾华   |
| 匡明   |
| 李军   |
| 陆君   |
| 曾华   |
| 匡明   |
| 李军   |
| 陆君   |
+--------+
8 rows in set (0.00 sec)

44、查询和“李军”同性别并同班的同学Sname.

mysql> select sname from students where ssex = (select ssex from students where sname = '李军' limit 1) and class = (select class from students where sname = '李军' limit 1) group by sname;
+--------+
| sname  |
+--------+
| 曾华   |
| 李军   |
+--------+
2 rows in set (0.00 sec)

45、查询所有选修“计算机导论”课程的“男”同学的成绩表

mysql> select * from students, courses, scores where courses.cname = '计算机导论' and students.ssex = '男' group by sname;
+-----+--------+------+---------------------+-------+-------+-----------------+-----+-----+-------+--------+
| sno | sname  | ssex | sbirthday           | class | cno   | cname           | tno | sno | cno   | degree |
+-----+--------+------+---------------------+-------+-------+-----------------+-----+-----+-------+--------+
| 105 | 匡明   | 男   | 1975-10-02 00:00:00 | 95031 | 3-105 | 计算机导论      | 825 | 103 | 3-245 |   86.0 |
| 108 | 曾华   | 男   | 1977-09-01 00:00:00 | 95033 | 3-105 | 计算机导论      | 825 | 103 | 3-245 |   86.0 |
| 101 | 李军   | 男   | 1976-02-20 00:00:00 | 95033 | 3-105 | 计算机导论      | 825 | 103 | 3-245 |   86.0 |
| 103 | 陆君   | 男   | 1974-06-03 00:00:00 | 95031 | 3-105 | 计算机导论      | 825 | 103 | 3-245 |   86.0 |
+-----+--------+------+---------------------+-------+-------+-----------------+-----+-----+-------+--------+
4 rows in set (0.00 sec)