18、SQL语句练习

MrJason...大约 8 分钟

SQL语句练习

1. 表结构

2. 插入数据

DROP TABLE IF EXISTS `COURSE`;
CREATE TABLE `COURSE` (
  `CNO` varchar(5) NOT NULL,
  `CNAME` varchar(10) NOT NULL,
  `TNO` varchar(10) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

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


DROP TABLE IF EXISTS `SCORE`;
CREATE TABLE `SCORE` (
  `SNO` varchar(3) NOT NULL,
  `CNO` varchar(5) NOT NULL,
  `DEGREE` decimal(10,1) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;


INSERT INTO `SCORE` VALUES ('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),('101','6-166',85.0),('107','6-106',79.0),('108','3-105',78.0),('108','6-166',81.0);

DROP TABLE IF EXISTS `STUDENT`;
CREATE TABLE `STUDENT` (
  `SNO` varchar(3) NOT NULL,
  `SNAME` varchar(4) NOT NULL,
  `SSEX` varchar(2) NOT NULL,
  `SBIRTHDAY` datetime DEFAULT NULL,
  `CLASS` varchar(5) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `STUDENT` VALUES ('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');


DROP TABLE IF EXISTS `TEACHER`;
CREATE TABLE `TEACHER` (
  `TNO` varchar(3) NOT NULL,
  `TNAME` varchar(4) NOT NULL,
  `TSEX` varchar(2) NOT NULL,
  `TBIRTHDAY` datetime NOT NULL,
  `PROF` varchar(6) DEFAULT NULL,
  `DEPART` varchar(10) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `TEACHER` VALUES ('804','李诚','男','1958-12-02 00:00:00','副教授','计算机系'),('856','张旭','男','1969-03-12 00:00:00','讲师','电子工程系'),('825','王萍','女','1972-05-05 00:00:00','助教','计算机系'),('831','刘冰','女','1977-08-14 00:00:00','助教','电子工程系');

3. 相关练习

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 *
from SCORE
where DEGREE > 60 and DEGREE < 80;

解法二

select *
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 *
from SCORE
where DEGREE = 85 or DEGREE = 86 or DEGREE = 88;

解法二

select *
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, 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。

select
  sno,
  CNO
from SCORE
where DEGREE = (
  select max(DEGREE)
  from SCORE
);

11、查询‘3-105’号课程的平均分。

select avg(DEGREE)
from SCORE
where CNO = '3-105';

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。
刚开始没做出来

select
  avg(DEGREE),
  CNO
from SCORE
where cno like '3%'
group by CNO
having count(*) > 5;

13、查询最低分大于70，最高分小于90的Sno列。

select SNO
from SCORE
group by SNO
having min(DEGREE) > 70 and max(DEGREE) < 90;

14、查询所有学生的Sname、Cno和Degree列。

select
  SNAME,
  CNO,
  DEGREE
from STUDENT, SCORE
where STUDENT.SNO = SCORE.SNO;

15、查询所有学生的Sno、Cname和Degree列。

select
  SCORE.SNO,
  CNO,
  DEGREE
from STUDENT, SCORE
where STUDENT.SNO = SCORE.SNO;

16、查询所有学生的Sname、Cname和Degree列。
一口气join 两张表我也是没人这么写的

SELECT
  A.SNAME,
  B.CNAME,
  C.DEGREE
FROM STUDENT A
  JOIN (COURSE B, SCORE C)
    ON A.SNO = C.SNO AND B.CNO = C.CNO;=

17、查询“95033”班所选课程的平均分。

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  numeric(3, 0),
  upp  numeric(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。

没做出来

SELECT
  A.SNO,
  A.CNO,
  B.RANK
FROM SCORE A, grade B
WHERE A.DEGREE BETWEEN B.LOW AND B.UPP
ORDER BY RANK;

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 > ALL (
  select DEGREE
  from SCORE
  where SNO = '109'
);

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学生记录
有点绕

select * from STUDENT where SNO
  in (select SNO
  from SCORE
  where DEGREE < (select MAX(DEGREE) 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 CNO = '3-105' and DEGREE > ALL (
  select DEGREE
  from SCORE
  where SNO = '109'
);

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
  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 COURSE
    inner join TEACHER on COURSE.TNO = TEACHER.TNO and 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 = (
  select TNO
  from COURSE
  where CNO = (select CNO
               from SCORE
               group by CNO
               having count(SNO) > 5)
);

25、查询95033班和95031班全体学生的记录。

select *
from STUDENT
where CLASS in ('95033', '95031');

26、查询存在有85分以上成绩的课程Cno.

很容易理解错误，是存在85分以上的课程

select cno
from SCORE
group by CNO
having MAX(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, COURSE
              where DEPART = '计算机系' and COURSE.TNO = TEACHER.TNO);

28、查询“计算机系”与“电子工程系“不同职称的教师的Tname和Prof
题目有点难理解

select
  tname,
  prof
from TEACHER
where depart = '计算机系' and prof not 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。
至少高于的玩法需要注意

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.

SELECT *
FROM SCORE
WHERE DEGREE > ALL (
  SELECT DEGREE
  FROM SCORE
  WHERE CNO = '3-245'
)
ORDER by DEGREE desc;

另一种

select *
from SCORE
where CNO = '3-105'
  and DEGREE > (
    select max(DEGREE)
    from SCORE
    where CNO = '3-245')
order by DEGREE desc
;

31、查询所有教师和同学的name、sex和birthday.

select
  TNAME     name,
  TSEX      sex,
  TBIRTHDAY birthday
from TEACHER
union
select
  sname     name,
  SSEX      sex,
  SBIRTHDAY birthday
from STUDENT;

32、查询所有“女”教师和“女”同学的name、sex和birthday.

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';

33、查询成绩比该课程平均成绩低的同学的成绩表。
外表的条件还是可以传递到子查询的

SELECT A.*
FROM SCORE A
WHERE DEGREE < (SELECT AVG(DEGREE)
                FROM SCORE B
                WHERE A.CNO = B.CNO);

34、查询所有任课教师的Tname和Depart.

select
  TNAME,
  DEPART
from TEACHER a
where exists(select *
             from COURSE b
             where a.TNO = b.TNO);

另一种解法

select TNAME, PROF
from TEACHER
where TNO in (
    select COURSE.TNO
    from COURSE
    where COURSE.TNO = TEACHER.TNO
)

35、查询所有未讲课的教师的Tname和Depart.

select
  TNAME,
  DEPART
from TEACHER a
where tno not in (select tno
                  from COURSE);

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(SSEX) > 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)
from STUDENT;

39、查询Student表中最大和最小的Sbirthday日期值。

select min(SBIRTHDAY) birthday
from STUDENT
union
select max(SBIRTHDAY) birthday
from STUDENT;

跟我的不一样，我在一条记录上实现

select min(SBIRTHDAY), max(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, year(now()) - year(SBIRTHDAY) desc;

我感觉不用计算年龄，直接用生日升序就可以

select *
from STUDENT
order by CLASS desc, SBIRTHDAY asc

41、查询“男”教师及其所上的课程。

select *
from TEACHER, COURSE
where TSEX = '男' and COURSE.TNO = TEACHER.TNO;

42、查询最高分同学的Sno、Cno和Degree列。

select
  sno,
  CNO,
  DEGREE
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.
多字段匹配玩法确实之前很少用

select sname
from STUDENT
where (SSEX, CLASS) = (select
                         SSEX,
                         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, STUDENT
where SCORE.SNO = STUDENT.SNO and SSEX = '男' and CNO = (
  select CNO
  from COURSE
  where CNAME = '计算机导论');

46、使用游标方式来同时查询每位同学的名字，他所选课程及成绩。
很少使用

declare
 cursor student_cursor is
  select S.SNO,S.SNAME,C.CNAME,SC.DEGREE as DEGREE
  from STUDENT S, COURSE C, SCORE SC
  where S.SNO=SC.SNO
  and SC.CNO=C.CNO;

  student_row student_cursor%ROWTYPE;

begin
  open student_cursor;
   loop
    fetch student_cursor INTO student_row;
    exit when student_cursor%NOTFOUND;
     dbms_output.put_line( student_row.SNO || '' || 

student_row.SNAME|| '' || student_row.CNAME || '' ||

student_row.DEGREE);
   end loop;
  close student_cursor;
END;
/

47、声明触发器指令，每当有同学转换班级时执行触发器显示当前和之前所在班级。

很少使用

CREATE OR REPLACE TRIGGER display_class_changes 
AFTER DELETE OR INSERT OR UPDATE ON student 
FOR EACH ROW 
WHEN (NEW.sno > 0) 

BEGIN 
   
   dbms_output.put_line('Old class: ' || :OLD.class); 
   dbms_output.put_line('New class: ' || :NEW.class); 
END; 
/ 


Update student
set class=95031
where sno=109;