自己学习,同时做个记录
原贴链接https://blog.youkuaiyun.com/flycat296/article/details/63681089
测试表格
学生
CREATE TABLE `student` (
`s_id` varchar(10) DEFAULT NULL,
`s_name` varchar(10) DEFAULT NULL,
`s_age` datetime DEFAULT NULL,
`s_sex` varchar(10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
insert into student values('01' , N'赵雷' , '1990-01-01' , N'男')
insert into student values('02' , N'钱电' , '1990-12-21' , N'男')
insert into student values('03' , N'孙风' , '1990-05-20' , N'男')
insert into student values('04' , N'李云' , '1990-08-06' , N'男')
insert into student values('05' , N'周梅' , '1991-12-01' , N'女')
insert into student values('06' , N'吴兰' , '1992-03-01' , N'女')
insert into student values('07' , N'郑竹' , '1989-07-01' , N'女')
insert into student values('08' , N'王菊' , '1990-01-20' , N'女')
老师
CREATE TABLE `teacher` (
`t_id` varchar(10) DEFAULT NULL,
`t_name` varchar(10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
insert into teacher values('01' , N'张三')
insert into teacher values('02' , N'李四')
insert into teacher values('03' , N'王五')
课程
CREATE TABLE `course` (
`c_id` varchar(10) DEFAULT NULL,
`c_name` varchar(10) DEFAULT NULL,
`t_id` varchar(10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
insert into course values('01' , N'语文' , '02')
insert into course values('02' , N'数学' , '01')
insert into course values('03' , N'英语' , '03')
学生成绩
CREATE TABLE `student_score` (
`s_id` varchar(10) DEFAULT NULL,
`c_id` varchar(10) DEFAULT NULL,
`score` decimal(18,1) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
insert into student_score values('01' , '01' , 80)
insert into student_score values('01' , '02' , 90)
insert into student_score values('01' , '03' , 99)
insert into student_score values('02' , '01' , 70)
insert into student_score values('02' , '02' , 60)
insert into student_score values('02' , '03' , 80)
insert into student_score values('03' , '01' , 80)
insert into student_score values('03' , '02' , 80)
insert into student_score values('03' , '03' , 80)
insert into student_score values('04' , '01' , 50)
insert into student_score values('04' , '02' , 30)
insert into student_score values('04' , '03' , 20)
insert into student_score values('05' , '01' , 76)
insert into student_score values('05' , '02' , 87)
insert into student_score values('06' , '01' , 31)
insert into student_score values('06' , '03' , 34)
insert into student_score values('07' , '02' , 89)
insert into student_score values('07' , '03' , 98)
1. 查询" 01 "课程比" 02 "课程成绩高的学生的信息及课程分数
1.1 查询" 01 "课程和" 02 "课程都有成绩的情况
1.2 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 )
1.3 查询不存在" 01 "课程但存在" 02 "课程的情况
2. 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
3. 查询在 SC 表存在成绩的学生信息
4. 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 )
4.1 查有成绩的学生信息
5. 查询「李」姓老师的数量
6. 查询学过「张三」老师授课的同学的信息
7. 查询没有学全所有课程的同学的信息
8. 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
9. 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
10. 查询没学过"张三"老师讲授的任一门课程的学生姓名
11. 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
12. 检索" 01 "课程分数小于 60,按分数降序排列的学生信息
13. 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
14. 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
15. 按各科成绩进行排序,并显示排名, Score 重复时保留名次空缺
15.1 按各科成绩进行排序,并显示排名, Score 重复时合并名次
16. 查询学生的总成绩,并进行排名,总分重复时保留名次空缺
16.1 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
17. 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
18. 查询各科成绩前三名的记录
19. 查询每门课程被选修的学生数
20. 查询出只选修两门课程的学生学号和姓名
21. 查询男生、女生人数
22. 查询名字中含有「风」字的学生信息
23. 查询同名同性学生名单,并统计同名人数
24. 查询 1990 年出生的学生名单
25. 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
26. 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
27. 查询课程名称为「数学」,且分数低于 60 的学生姓名和分数
28. 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)
29. 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
30. 查询不及格的课程
31. 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
32. 求每门课程的学生人数
33. 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
34. 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
35. 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
36. 查询每门功成绩最好的前两名
37. 统计每门课程的学生选修人数(超过 5 人的课程才统计)。
38. 检索至少选修两门课程的学生学号
39. 查询选修了全部课程的学生信息
40. 查询各学生的年龄,只按年份来算
41. 按照出生日期来算,当前月日 < 出生年月的月日则,年龄减一
42. 查询本周过生日的学生
43. 查询下周过生日的学生
44. 查询本月过生日的学生
45. 查询下月过生日的学生
1.
SELECT student.*,a.score FROM student,
(SELECT * FROM student_score WHERE c_id = '01')a LEFT JOIN
(SELECT * FROM student_score WHERE c_id = '02')b
ON a.s_id = b.s_id WHERE a.score > b.score AND student.s_id in (a.s_id)
1.1
SELECT * FROM
(SELECT * FROM student_score WHERE c_id = '01')a LEFT JOIN
(SELECT * FROM student_score WHERE c_id = '02')b ON a.s_id = b.s_id
WHERE b.s_id IS NOT NULL
1.2
SELECT * FROM
(SELECT * FROM student_score WHERE c_id = '01')a LEFT JOIN
(SELECT * FROM student_score WHERE c_id = '02')b ON a.s_id = b.s_id
1.3
SELECT * FROM student_score WHERE c_id = '02' AND s_id NOT in
(SELECT s_id FROM student_score WHERE c_id = '01')
2.
SELECT student.s_id,student.s_name,a.avg FROM student LEFT JOIN
(SELECT s_id,Avg(score)avg FROM student_score GROUP BY s_id)a
ON student.s_id = a.s_id WHERE a.avg >= 60
3.
SELECT * FROM student WHERE s_id in (SELECT DISTINCT s_id FROM student_score )
4.
SELECT student.s_id,student.s_name,a.选课总数 ,a.总成绩 FROM student
LEFT JOIN (SELECT s_id,COUNT(c_id)选课总数,SUM(score)总成绩 FROM student_score GROUP BY s_id)a
ON student.s_id = a.s_id
4.1
SELECT * FROM student WHERE s_id in (SELECT DISTINCT s_id FROM student_score)
5.
SELECT COUNT(*) FROM teacher WHERE t_name LIKE '李%'
6.
SELECT * FROM student WHERE s_id in (
SELECT s_id FROM student_score WHERE c_id =
(SELECT c_id FROM course WHERE t_id =
(SELECT t_id FROM teacher WHERE t_name = '张三')))
7.
SELECT * FROM student WHERE s_id in
(SELECT s_id FROM student_score GROUP BY s_id HAVING COUNT(c_id) < 3)
8.
SELECT * FROM student WHERE s_id in
(SELECT DISTINCT s_id FROM student_score WHERE c_id in
(SELECT c_id FROM student_score WHERE s_id = '01'))
9.
SELECT * FROM student WHERE s_id != '01' AND s_id in
(SELECT s_id FROM student_score GROUP BY s_id HAVING COUNT(c_id) = 3)
10.
SELECT student.s_name FROM student WHERE s_id NOT in
(SELECT s_id FROM student_score WHERE c_id =
(SELECT c_id FROM course WHERE t_id =
(SELECT t_id FROM teacher WHERE t_name = '张三')))
11.
SELECT student.s_id,student.s_name,a.平均成绩 FROM student JOIN
(SELECT s_id,AVG(score)平均成绩 FROM student_score WHERE score < 60 GROUP BY s_id HAVING COUNT(score) >=2)a
ON student.s_id = a.s_id
12.
SELECT student.* FROM student JOIN
(SELECT s_id,score FROM student_score WHERE c_id = '01' AND score < 60)a
ON student.s_id = a.s_id ORDER BY a.score DESC
13.
SELECT student_score.*,a.平均成绩 FROM student_score LEFT JOIN
(SELECT *,AVG(score)平均成绩 FROM student_score GROUP BY s_id)a
ON student_score.s_id = a.s_id
ORDER BY 平均成绩 DESC (多行展示)
select s_id,max(case c_id when '01' then score else 0 end)'01',
max(case c_id when '02' then score else 0 end)'02',
MAX(case c_id when '03' then score else 0 end)'03',AVG(score)平均分 from student_score
group by s_id order by 平均分 desc (按s_id合并成一行)
14.特别难
15.
SELECT a.* , @curRank := @curRank + 1 AS rank FROM
student_score a,(SELECT @curRank :=0) b ORDER BY score DESC
15.1
SELECT a.*,
CASE
WHEN @prevRank = score THEN
@curRank
WHEN @prevRank := score THEN
@curRank := @curRank + 1
END AS rank
FROM
student_score a,(SELECT @curRank := 0 ,@prevRank = NULL) b
ORDER BY score DESC
16.
SELECT s.*,@curRank := @curRank + 1 AS rank FROM
(SELECT s_id,SUM(score)总成绩 FROM student_score GROUP BY s_id ORDER BY 总成绩 DESC)s,
(SELECT @curRank := 0)r
ORDER BY rank ASC
16.1
SELECT s.*,
CASE
WHEN @prevRank = 总成绩 THEN @curRank
WHEN @prevRank := 总成绩 THEN @curRank := @curRank + 1
END AS rank FROM
(SELECT s_id,SUM(score)总成绩 FROM student_score GROUP BY s_id ORDER BY 总成绩 DESC)s,
(SELECT @curRank := 0,@prevRank = NULL)r ORDER BY rank ASC
17.难
18.
SELECT c_id,score FROM student_score a
WHERE (SELECT COUNT(*) FROM student_score WHERE c_id = a.c_id AND score>a.score)<3
ORDER BY a.c_id ASC,a.score DESC
19.
SELECT c_id,COUNT(*)人数 FROM student_score GROUP BY c_id
20.
SELECT a.s_id,COUNT(c_id)课程数,b.s_name 学生 FROM student_score a,student b
WHERE a.s_id = b.s_id
GROUP BY a.s_id HAVING 课程数 = 2
21.
SELECT s_sex,COUNT(s_sex) FROM student GROUP BY s_sex
22.
SELECT * FROM student WHERE s_name LIKE '%风%'
23.
24.
SELECT * FROM student WHERE s_age LIKE '%1990%'
25.
SELECT c_id,AVG(score)平均成绩 FROM student_score
GROUP BY c_id ORDER BY 平均成绩 DESC,c_id ASC
26.
SELECT * FROM student a,
(SELECT s_id,AVG(score)avg FROM student_score GROUP BY s_id) b
WHERE a.s_id = b.s_id AND b.avg >= 85
ORDER BY b.avg DESC
27.
SELECT * FROM student WHERE s_id in (
SELECT s_id FROM student_score WHERE c_id =
(SELECT c_id FROM course WHERE c_name = '数学')
AND score < 60)
28.
横向
SELECT s_name,b.score 语文,c.score 数学,d.score 英语 FROM student a
LEFT JOIN (SELECT s_id,score FROM student_score WHERE c_id = '01')b ON a.s_id = b.s_id
LEFT JOIN (SELECT s_id,score FROM student_score WHERE c_id = '02')c ON a.s_id = c.s_id
LEFT JOIN (SELECT s_id,score FROM student_score WHERE c_id = '03')d ON a.s_id = d.s_id
纵向
SELECT a.*,b.* FROM student a LEFT JOIN student_score b ON a.s_id = b.s_id
29.
SELECT a.s_name,c.c_name,b.score FROM student a,course c,(SELECT s_id,c_id,score FROM student_score WHERE score > 70) b
WHERE a.s_id = b.s_id AND c.c_id = b.c_id
30.
SELECT c_name FROM course WHERE c_id in
(SELECT c_id FROM student_score WHERE score < 60)
31.
SELECT s_id,s_name FROM student WHERE s_id in
(SELECT s_id FROM student_score WHERE c_id = '01' AND score > 80)
32.
SELECT c_id ,COUNT(s_id)人数 FROM student_score GROUP BY c_id
33.
SELECT a.*,b.score FROM student a,
(SELECT s_id,MAX(score)score FROM student_score WHERE c_id =
(SELECT c_id FROM course WHERE t_id =
(SELECT t_id FROM teacher WHERE t_name = '张三'))
ORDER BY score DESC)b WHERE a.s_id = b.s_id
34.
35.
36.
37.
38.
SELECT s_id FROM student_score GROUP BY s_id
HAVING COUNT(c_id)>=2
39.
SELECT * FROM student WHERE s_id in
(SELECT s_id FROM student_score GROUP BY s_id
HAVING COUNT(c_id)=3)