学生表 Student
create table Student(SId varchar(10),Sname varchar(10),Sage datetime,Ssex varchar(10));
insert into Student values('01' , '赵雷' , '1990-01-01' , '男');
insert into Student values('02' , '钱电' , '1990-12-21' , '男');
insert into Student values('03' , '孙风' , '1990-12-20' , '男');
insert into Student values('04' , '李云' , '1990-12-06' , '男');
insert into Student values('05' , '周梅' , '1991-12-01' , '女');
insert into Student values('06' , '吴兰' , '1992-01-01' , '女');
insert into Student values('07' , '郑竹' , '1989-01-01' , '女');
insert into Student values('09' , '张三' , '2017-12-20' , '女');
insert into Student values('10' , '李四' , '2017-12-25' , '女');
insert into Student values('11' , '李四' , '2012-06-06' , '女');
insert into Student values('12' , '赵六' , '2013-06-13' , '女');
insert into Student values('13' , '孙七' , '2014-06-01' , '女');
科目表 Course
create table Course(CId varchar(10),Cname nvarchar(10),TId varchar(10));
insert into Course values('01' , '语文' , '02');
insert into Course values('02' , '数学' , '01');
insert into Course values('03' , '英语' , '03');
教师表 Teacher
create table Teacher(TId varchar(10),Tname varchar(10));
insert into Teacher values('01' , '张三');
insert into Teacher values('02' , '李四');
insert into Teacher values('03' , '王五');
成绩表 SC
create table SC(SId varchar(10),CId varchar(10),score decimal(18,1));
insert into SC values('01' , '01' , 80);
insert into SC values('01' , '02' , 90);
insert into SC values('01' , '03' , 99);
insert into SC values('02' , '01' , 70);
insert into SC values('02' , '02' , 60);
insert into SC values('02' , '03' , 80);
insert into SC values('03' , '01' , 80);
insert into SC values('03' , '02' , 80);
insert into SC values('03' , '03' , 80);
insert into SC values('04' , '01' , 50);
insert into SC values('04' , '02' , 30);
insert into SC values('04' , '03' , 20);
insert into SC values('05' , '01' , 76);
insert into SC values('05' , '02' , 87);
insert into SC values('06' , '01' , 31);
insert into SC values('06' , '03' , 34);
insert into SC values('07' , '02' , 89);
insert into SC values('07' , '03' , 98);
练习题目
1.查询" 01 "课程比" 02 "课程成绩高的学生的信息及课程分数
2.查询同时存在" 01 "课程和" 02 "课程的情况
3.查询存在" 01 "课程但可能不存在" 02 "课程的情况(不存在时显示为 null )
4.查询不存在" 01 "课程但存在" 02 "课程的情况
5.查询平均成绩大于等于 60 分的同学的学生编号和学生姓名和平均成绩
6.查询在 SC 表存在成绩的学生信息
7.查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩(没成绩的显示为 null )
8.查有成绩的学生信息
9.查「李」姓老师的数量
10.查询学过「张三」老师授课的同学的信息
11.查询没有学全所有课程的同学的信息
12.查询至少有一门课与学号为" 01 "的同学所学相同的同学的信息
13.查询和" 01 "号的同学学习的课程 完全相同的其他同学的信息
14.查询没学过"张三"老师讲授的任一门课程的学生姓名
15.查询两门及其以上不及格课程的同学的学号,姓名及其平均成绩
16.检索" 01 "课程分数小于 60,按分数降序排列的学生信息
17.按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
18.查询各科成绩最高分、最低分和平均分:
以如下形式显示:课程 ID,课程 name,最高分,最低分,平均分,及格率,中等率,优良率,优秀率
及格为>=60,中等为:70-80,优良为:80-90,优秀为:>=90
要求输出课程号和选修人数,查询结果按人数降序排列,若人数相同,按课程号升序排列
19.按各科成绩进行排序,并显示排名, Score 重复时保留名次空缺
20.查询学生的总成绩,并进行排名,总分重复时保留名次空缺
21.查询学生的总成绩,并进行排名,总分重复时不保留名次空缺
22.统计各科成绩各分数段人数:课程编号,课程名称,[100-85],[85-70],[70-60],[60-0] 及所占百分比
23.查询各科成绩前三名的记录
24.查询每门课程被选修的学生数
25.查询出只选修两门课程的学生学号和姓名
26.查询男生、女生人数
27.查询名字中含有「风」字的学生信息
28.查询同名同性学生名单,并统计同名人数
29.查询 1990 年出生的学生名单
30.查询每门课程的平均成绩,结果按平均成绩降序排列,平均成绩相同时,按课程编号升序排列
31.查询平均成绩大于等于 85 的所有学生的学号、姓名和平均成绩
32.查询课程名称为「数学」,且分数低于 60 的学生姓名和分数
33.查询所有学生的课程及分数情况(存在学生没成绩,没选课的情况)
34.查询任何一门课程成绩在 70 分以上的姓名、课程名称和分数
35.查询不及格的课程
36.查询课程编号为 01 且课程成绩在 80 分以上的学生的学号和姓名
37.求每门课程的学生人数
38.成绩不重复,查询选修「张三」老师所授课程的学生中,成绩最高的学生信息及其成绩
39.成绩有重复的情况下,查询选修「张三」老师所授课程的学生中,成绩最高的学生信息及其成绩
40.查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩
41.查询每门功成绩最好的前两名
42.统计每门课程的学生选修人数(超过 5 人的课程才统计)。
43.检索至少选修两门课程的学生学号
44.查询选修了全部课程的学生信息
45.查询各学生的年龄,只按年份来算
46.按照出生日期来算,当前月日 < 出生年月的月日则,年龄减一
47.查询本周过生日的学生
48.查询下周过生日的学生
49.查询本月过生日的学生
50.查询下月过生日的学生
答案
1.查询" 01 "课程比" 02 "课程成绩高的学生的信息及课程分数
SELECT
s.*,
a.score 语文,
b.score 数学
FROM
student s,
(SELECT * FROM sc WHERE sc.CId=01) a,
(SELECT * FROM sc WHERE sc.CId=02) b
WHERE
s.SId=a.SId
AND
a.SId=b.SId
AND
a.score>b.score;
SELECT
*
FROM
student s
RIGHT JOIN
(SELECT a.SId,a.score 语文,b.score 数学
FROM
(SELECT * FROM sc WHERE sc.CId=01) a,
(SELECT * FROM sc WHERE sc.CId=02) b
WHERE
a.SId=b.SId
AND
a.score>b.score) c
ON
s.SId=c.SId
SELECT
*
FROM
(SELECT a.SId,a.score 语文,b.score 数学
FROM
(SELECT * FROM sc WHERE sc.CId=01) a,
(SELECT * FROM sc WHERE sc.CId=02) b
WHERE
a.SId=b.SId
AND
a.score>b.score) c
LEFT JOIN
student s
ON
s.SId=c.SId
2.查询同时存在" 01 "课程和" 02 "课程的情况
SELECT
*
FROM
(SELECT * FROM sc WHERE sc.CId=01) a,
(SELECT * FROM sc WHERE sc.CId=02) b
WHERE
a.SId=b.SId;
- 查询存在" 01 "课程但可能不存在" 02 "课程的情况(不存在时显示为 NULL )
SELECT
*
FROM
(SELECT * FROM sc WHERE sc.CId=01) a
LEFT JOIN
(SELECT * FROM sc WHERE sc.CId=02) b
ON
a.SId=b.SId
SELECT
*
FROM
(SELECT * FROM sc WHERE sc.CId=02) b
RIGHT JOIN
(SELECT * FROM sc WHERE sc.CId=01) a
ON
a.SId=b.SId
4.查询不存在" 01 "课程但存在" 02 "课程的情况
SELECT
*
FROM
sc
WHERE
sc.SId NOT IN (SELECT SId FROM sc WHERE sc.CId=01)
AND
sc.CId=02
5.查询平均成绩大于等于 60 分的同学的学生编号和学生姓名和平均成绩
SELECT
s.SId,
s.Sname,
AVG(sc.score) 平均分
FROM
student s,
sc
WHERE
s.SId=sc.SId
GROUP BY
sc.SId
HAVING
AVG(sc.score)>60
SELECT s.SId,sname,a 平均分
FROM
student s,
(SELECT SId, AVG(score) a
FROM sc
GROUP BY SId
HAVING AVG(score)> 60) c
WHERE
s.SId = c.SId;
6.查询在 SC 表存在成绩的学生信息
SELECT
DISTINCT
s.*
FROM
student s,
sc
WHERE
sc.SId=s.SId
7.查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩(没成绩的显示为 null )
SELECT
s.SId,
S.Sname,
c.a 选课总数,
c.b 总成绩
FROM
student s
LEFT JOIN
(SELECT
sc.SId,
COUNT(sc.CId) a,
SUM(sc.score) b
FROM
sc
GROUP BY
sc.SId) c
ON
s.SId=c.SId
8.查有成绩的学生信息
SELECT
*
FROM
student s
WHERE
EXISTS
(SELECT
*
FROM
sc
WHERE
s.SId=sc.SId)
SELECT
*
FROM
student s
WHERE
s.SId
IN
(SELECT
sc.SId
FROM
sc)
9.查「李」姓老师的数量
SELECT
COUNT(TId)
FROM
teacher
WHERE
Tname
LIKE
'李%'
10.查询学过「张三」老师授课的同学的信息
SELECT
s.*
FROM
student s,sc,course c,teacher t
WHERE
t.Tname='张三'
AND
t.TId=c.TId
AND
c.CId=sc.CId
AND
sc.SId=s.SId
11.查询没有学全所有课程的同学的信息
SELECT
*
FROM
student
WHERE SId NOT IN
(SELECT
SId
FROM
sc
GROUP BY SId)
12.查询至少有一门课与学号为" 01 "的同学所学相同的同学的信息
SELECT
*
FROM
student
WHERE SId IN
(SELECT
SId
FROM
sc
WHERE CId IN
(SELECT
CId
FROM
sc
WHERE sc.SId = 01)
AND SId <> 01)
13.查询和" 01 "号的同学学习的课程 完全相同的其他同学的信息
SELECT
s.*
FROM
student s,
(SELECT DISTINCT
SId
FROM
sc
WHERE SId NOT IN
(SELECT
SId
FROM
sc
WHERE CId NOT IN
(SELECT
CId
FROM
sc
WHERE SId = 01))
AND SId NOT IN
(SELECT
SId
FROM
sc
GROUP BY SId
HAVING COUNT(CId) <
(SELECT
COUNT(CId)
FROM
sc
WHERE SId = 01))
AND SId <> 01) a
WHERE s.SId = a.SId
14.查询没学过"张三"老师讲授的任一门课程的学生姓名
SELECT
*
FROM
student
WHERE SId NOT IN
(SELECT
SId
FROM
teacher t,
course c,
sc
WHERE t.Tname = '张三'
AND t.TId = c.TId
AND c.TId = sc.CId)
15.查询两门及其以上不及格课程的同学的学号,姓名及其平均成绩
SELECT
s.*,
c.a 平均分
FROM
student s,
(SELECT
SId,
AVG(score) a
FROM
sc
WHERE SId IN
(SELECT
SId
FROM
sc
WHERE score < 60
GROUP BY SId
HAVING COUNT(SId) > 1)
GROUP BY SId) c
WHERE s.SId = c.SId
16.检索" 01 "课程分数小于 60,按分数降序排列的学生信息
SELECT
s.*,
sc.score
FROM
student s,
sc
WHERE s.SId = sc.SId
AND sc.CId = 01
AND sc.score < 60
ORDER BY sc.score DESC
17.按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
SELECT
sc.*,
c.a 平均成绩
FROM
sc,
(SELECT
SId,
AVG(score) a
FROM
sc
GROUP BY SId) c
WHERE sc.SId = c.SId
ORDER BY 平均成绩 DESC
18.查询各科成绩最高分、最低分和平均分:
以如下形式显示:课程 ID,课程 name,最高分,最低分,平均分,及格率,中等率,优良率,优秀率
及格为>=60,中等为:70-80,优良为:80-90,优秀为:>=90
要求输出课程号和选修人数,查询结果按人数降序排列,若人数相同,按课程号升序排列
SELECT
sc.CId 课程ID,
c.Cname 课程name,
MAX(score) 最高分,
MIN(score) 最低分,
AVG(score) 平均分,
SUM(
CASE
WHEN sc.score >= 60
THEN 1
ELSE 0
END
) / COUNT(*) 及格率,
SUM(
CASE
WHEN sc.score >= 70
AND sc.score < 80
THEN 1
ELSE 0
END
) / COUNT(*) AS 中等率,
SUM(
CASE
WHEN sc.score >= 80
AND sc.score < 90
THEN 1
ELSE 0
END
) / COUNT(*) AS 优良率,
SUM(
CASE
WHEN sc.score >= 90
THEN 1
ELSE 0
END
) / COUNT(*) AS 优秀率
FROM
sc,
course c
WHERE sc.CId = c.CId
GROUP BY sc.CId
ORDER BY COUNT(*) DESC,
sc.CId
19.按各科成绩进行排序,并显示排名, Score 重复时保留名次空缺
SELECT
a.cid,
a.sid,
a.score,
COUNT(b.score) + 1 rank
FROM
sc a
LEFT JOIN sc b
ON a.score < b.score
AND a.CId = b.CId
GROUP BY a.CId,
a.SId,
a.score
ORDER BY a.cid,
rank ASC
20.查询学生的总成绩,并进行排名,总分重复时保留名次空缺
SELECT a.sid,a.a 总成绩, COUNT(b.a)+1 排名 FROM
(SELECT sid,SUM(score) a FROM sc GROUP BY sid) a
LEFT JOIN
(SELECT sid,SUM(score) a FROM sc GROUP BY sid) b
ON a.a<b.a
GROUP BY sid
ORDER BY 排名 ASC
21.查询学生的总成绩,并进行排名,总分重复时不保留名次空缺
SET @crank = 0 ;
SELECT
sid,
总成绩,
@crank := @crank + 1 rank
FROM
(SELECT
sid,
SUM(score) 总成绩
FROM
sc
GROUP BY sid
ORDER BY SUM(score) DESC) a
22.统计各科成绩各分数段人数:课程编号,课程名称,[100-85],[85-70],[70-60],[60-0] 及所占百分比
SELECT c.cname, c.cid,
SUM(CASE WHEN sc.score<=100 AND sc.score>85 THEN 1 ELSE 0 END)/COUNT(*) "[100-85]",
SUM(CASE WHEN sc.score<=85 AND sc.score>70 THEN 1 ELSE 0 END)/COUNT(*) "[85-70]",
SUM(CASE WHEN sc.score<=70 AND sc.score>60 THEN 1 ELSE 0 END)/COUNT(*) "[70-60]",
SUM(CASE WHEN sc.score<=60 AND sc.score>0 THEN 1 ELSE 0 END)/COUNT(*) "[60-0]"
FROM sc LEFT JOIN course c
ON sc.cid = c.cid
GROUP BY sc.cid;
23.查询各科成绩前三名的记录
SELECT
*
FROM
sc
WHERE
(SELECT
COUNT(*)
FROM
sc AS a
WHERE sc.cid = a.cid
AND sc.score < a.score) < 3
ORDER BY cid ASC,
sc.score DESC ;
SELECT
a.sid,
a.cid,
a.score
FROM
sc a
LEFT JOIN sc b
ON a.cid = b.cid
AND a.score < b.score
GROUP BY a.cid,
a.sid
HAVING COUNT(b.cid) < 3
ORDER BY a.cid ;
24.查询每门课程被选修的学生数
SELECT
cid 课程,
COUNT(sid) 人数
FROM
sc
GROUP BY cid
25.查询出只选修两门课程的学生学号和姓名
SELECT
s.*
FROM
student s,
sc
WHERE s.sid = sc.sid
GROUP BY sc.sid
HAVING COUNT(sc.cid) = 2
26.查询男生、女生人数
SELECT
Ssex 性别,
COUNT(Ssex) 数量
FROM
student
GROUP BY Ssex
27.查询名字中含有「风」字的学生信息
SELECT
*
FROM
student
WHERE Sname LIKE '%风%'
28.查询同名同性学生名单,并统计同名人数
SELECT
Sname,
COUNT(*)
FROM
student
GROUP BY Sname
HAVING COUNT(*) > 1
29.查询 1990 年出生的学生名单
SELECT
sname
FROM
student
WHERE YEAR(sage) = 1990
30.查询每门课程的平均成绩,结果按平均成绩降序排列,平均成绩相同时,按课程编号升序排列
SELECT
c.cname,
SUM(sc.score) / COUNT(sc.score) 平均成绩
FROM
sc,
course c
WHERE sc.CId = c.CId
GROUP BY sc.CId
ORDER BY 平均成绩 DESC, c.CId ASC
31.查询平均成绩大于等于 85 的所有学生的学号、姓名和平均成绩
SELECT
s.sid,
s.sname,
AVG(score) 平均成绩
FROM
student s,
sc
WHERE s.sid = sc.sid
GROUP BY sid
HAVING AVG(sc.score) >= 85
32.查询课程名称为「数学」,且分数低于 60 的学生姓名和分数
SELECT
s.sname,
sc.score
FROM
course c,
sc,
student s
WHERE c.cid = sc.cid
AND sc.sid = s.sid
AND c.cname = '数学'
AND sc.score < 60
33.查询所有学生的课程及分数情况(存在学生没成绩,没选课的情况)
SELECT
s.sname,
sc.cid,
sc.score
FROM
student s
LEFT JOIN sc
ON s.sid = sc.sid
34.查询任何一门课程成绩在 70 分以上的姓名、课程名称和分数
SELECT
s.sname,
c.cname,
sc.score
FROM
student s,
sc,
course c
WHERE s.sid = sc.sid
AND c.cid = sc.cid
AND sc.score > 70
35.查询不及格的课程
SELECT DISTINCT
c.cname 课程
FROM
course c,
sc
WHERE c.cid = sc.cid
AND sc.score < 60
SELECT
c.cname 课程
FROM
sc,
course c
WHERE sc.cid = c.cid
AND sc.score < 60
GROUP BY sc.cid
36.查询课程编号为 01 且课程成绩在 80 分以上的学生的学号和姓名
SELECT
s.sid,
s.sname
FROM
student s,
sc
WHERE sc.sid = s.sid
AND sc.cid = 01
AND sc.score >= 80
37.求每门课程的学生人数
SELECT
c.cname 课程,
COUNT(sc.sid)
FROM
sc,
course c
WHERE c.cid = sc.cid
GROUP BY sc.cid
38.成绩不重复,查询选修「张三」老师所授课程的学生中,成绩最高的学生信息及其成绩
SELECT
s.*,
sc.score
FROM
student s,
sc,
teacher t,
course c
WHERE s.sid = sc.sid
AND sc.cid = c.cid
AND c.tid = t.tid
AND t.tname = '张三'
HAVING MAX(sc.score)
SELECT
s.*,
sc.score
FROM
student s,
sc,
teacher t,
course c
WHERE s.sid = sc.sid
AND sc.cid = c.cid
AND c.tid = t.tid
AND t.tname = '张三'
ORDER BY sc.score DESC
LIMIT 1
39.成绩有重复的情况下,查询选修「张三」老师所授课程的学生中,成绩最高的学生信息及其成绩
先修改原始数据
UPDATE
sc
SET
score = 90
WHERE sid = "07"
AND cid = "02" ;
SELECT
s.*,
sc.score,
sc.cid
FROM
student s,
teacher t,
course c,
sc
WHERE t.tid = c.tid
AND sc.sid = s.sid
AND sc.cid = c.cid
AND t.tname = "张三"
AND sc.score =
(SELECT
MAX(sc.score)
FROM
sc,
student s,
teacher t,
course c
WHERE t.tid = c.tid
AND sc.sid = s.sid
AND sc.cid = c.cid
AND t.tname = "张三") ;
40.查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩
SELECT
a.*
FROM
sc a
INNER JOIN sc b
ON a.sid = b.sid
AND a.cid != b.cid
AND a.score = b.score
GROUP BY a.sid,
a.cid
41.查询每门功成绩最好的前两名
SELECT
a.*
FROM
sc a
LEFT JOIN sc b
ON a.cid = b.cid
AND a.score < b.score
GROUP BY a.cid,
a.sid
HAVING COUNT(b.cid) < 2
ORDER BY a.cid ASC
42.统计每门课程的学生选修人数(超过 5 人的课程才统计)
SELECT
sc.cid
FROM
sc
GROUP BY cid
HAVING COUNT(*) > 5
43.检索至少选修两门课程的学生学号
SELECT
sid
FROM
sc
GROUP BY sid
HAVING COUNT(*) >= 2
44.查询选修了全部课程的学生信息
SELECT
s.*
FROM
student s,
sc
WHERE s.sid = sc.sid
GROUP BY sid
HAVING COUNT(sc.cid) =
(SELECT
COUNT(*)
FROM
course)
45.查询各学生的年龄,只按年份来算
SELECT
sname,
YEAR(NOW()) - YEAR(sage) 年龄
FROM
student
46.按照出生日期来算,当前月日 < 出生年月的月日则,年龄减一
SELECT
sname,
TIMESTAMPDIFF(YEAR,sage,NOW()) 年龄
FROM
student
47.查询本周过生日的学生
SELECT
sname
FROM
student
WHERE
WEEKOFYEAR(sage)=WEEKOFYEAR(NOW())
48.查询下周过生日的学生
SELECT
sname
FROM
student
WHERE
WEEKOFYEAR(sage)=WEEKOFYEAR(NOW())+1
49.查询本月过生日的学生
SELECT
sname
FROM
student
WHERE
MONTH(sage)=MONTH(NOW())
50.查询下月过生日的学生
SELECT
sname
FROM
student
WHERE
MONTH(sage)=MONTH(NOW())+1