SQL练习题

数据表介绍

–1.学生表

Student(SId,Sname,Sage,Ssex)
--SId 学生编号,Sname 学生姓名,Sage 出生年月,Ssex 学生性别

–2.课程表

Course(CId,Cname,TId)
--CId 课程编号,Cname 课程名称,TId 教师编号

–3.教师表

Teacher(TId,Tname)
--TId 教师编号,Tname 教师姓名

–4.成绩表

SC(SId,CId,score)
--SId 学生编号,CId 课程编号,score 分数

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);

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 AS score_01, b.score AS score_02
FROM Student s
JOIN SC a ON s.SId = a.SId AND a.CId = '01'
JOIN SC b ON s.SId = b.SId AND b.CId = '02'
WHERE a.score > b.score;

1.1 查询同时存在"01"课程和"02"课程的情况

SELECT s.* FROM Student s
WHERE s.SId IN (SELECT SId FROM SC WHERE CId='01')
AND s.SId IN (SELECT SId FROM SC WHERE CId='02');

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)

SELECT s.* 
FROM Student s
WHERE s.SId IN (SELECT SId FROM SC WHERE CId='01')
AND s.SId IN (SELECT SId FROM SC WHERE CId='02');

1.3 查询不存在"01"课程但存在"02"课程的情况

SELECT s.* FROM Student s
WHERE s.SId NOT IN (SELECT SId FROM SC WHERE CId='01')
AND s.SId IN (SELECT SId FROM SC WHERE CId='02');

2. 查询平均成绩大于等于60分的同学的学生编号、姓名和平均成绩

SELECT s.SId, s.Sname, AVG(sc.score) AS avg_score
FROM Student s
JOIN SC sc ON s.SId = sc.SId
GROUP BY s.SId, s.Sname
HAVING avg_score >= 60;

3. 查询在SC表存在成绩的学生信息

SELECT DISTINCT s.* FROM Student s
JOIN SC sc ON s.SId = sc.SId;

4. 查询所有同学的学生编号、姓名、选课总数、总成绩

SELECT s.SId, s.Sname, COUNT(sc.CId) AS total_course, SUM(sc.score) AS total_score
FROM Student s
LEFT JOIN SC sc ON s.SId = sc.SId
GROUP BY s.SId, s.Sname;

4.1 查有成绩的学生信息

SELECT s.* FROM Student s
WHERE EXISTS (SELECT 1 FROM SC WHERE SId = s.SId);

5. 查询「李」姓老师的数量

SELECT COUNT(*) FROM Teacher WHERE Tname LIKE '李%';

6. 查询学过「张三」老师授课的同学的信息

SELECT s.* FROM Student s
JOIN SC sc ON s.SId = sc.SId
JOIN Course c ON sc.CId = c.CId
JOIN Teacher t ON c.TId = t.TId
WHERE t.Tname = '张三';

7. 查询没有学全所有课程的同学的信息

SELECT s.* FROM Student s
WHERE s.SId NOT IN (SELECT SId FROM SCGROUP BY SIdHAVING COUNT(DISTINCT CId) = (SELECT COUNT(*) FROM Course)
);

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

SELECT DISTINCT s.* FROM Student s
JOIN SC sc ON s.SId = sc.SId
WHERE sc.CId IN (SELECT CId FROM SC WHERE SId = '01') AND s.SId != '01';

9. 查询和"01"号同学学习的课程完全相同的其他同学的信息

SELECT s.* FROM Student s
WHERE s.SId IN (SELECT SId FROM SCWHERE SId != '01'GROUP BY SIdHAVING GROUP_CONCAT(CId ORDER BY CId) = (SELECT GROUP_CONCAT(CId ORDER BY CId) FROM SC WHERE SId = '01')
);

10. 查询没学过"张三"老师授课的学生姓名

SELECT s.Sname FROM Student s
WHERE s.SId NOT IN (SELECT sc.SId FROM SC scJOIN Course c ON sc.CId = c.CIdJOIN Teacher t ON c.TId = t.TIdWHERE t.Tname = '张三'
);

11. 查询两门及以上不及格课程的同学的学号、姓名及其平均成绩

SELECT s.SId, s.Sname, AVG(sc.score) AS avg_score
FROM Student s
JOIN SC sc ON s.SId = sc.SId
WHERE sc.score < 60
GROUP BY s.SId, s.Sname
HAVING COUNT(*) >= 2;

12. 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
JOIN SC sc ON s.SId = sc.SId
WHERE sc.CId = '01' AND sc.score < 60
ORDER BY sc.score DESC;

13. 按平均成绩从高到低显示所有学生的所有课程成绩及平均成绩

SELECT s.SId, s.Sname, sc.CId, sc.score, AVG(sc.score) OVER (PARTITION BY s.SId) AS avg_score
FROM Student s
JOIN SC sc ON s.SId = sc.SId
ORDER BY avg_score DESC;

14. 查询各科成绩最高分、最低分、平均分及分段人数比例

SELECT c.CId,c.Cname,MAX(sc.score) AS 最高分,MIN(sc.score) AS 最低分,AVG(sc.score) AS 平均分,COUNT(*) AS 选修人数,SUM(CASE WHEN sc.score >= 85 THEN 1 ELSE 0 END)/COUNT(*) AS 优秀率,SUM(CASE WHEN sc.score >= 70 AND sc.score < 85 THEN 1 ELSE 0 END)/COUNT(*) AS 良好率,SUM(CASE WHEN sc.score >= 60 AND sc.score < 70 THEN 1 ELSE 0 END)/COUNT(*) AS 及格率,SUM(CASE WHEN sc.score < 60 THEN 1 ELSE 0 END)/COUNT(*) AS 不及格率
FROM SC sc
JOIN Course c ON sc.CId = c.CId
GROUP BY c.CId, c.Cname
ORDER BY 选修人数 DESC, c.CId;

15. 按各科成绩排序并显示排名（保留空缺）

SELECT CId, SId, score, RANK() OVER (PARTITION BY CId ORDER BY score DESC) AS `rank`
FROM SC;

15.1 按各科成绩排序并显示排名（合并名次）

SELECT CId, SId, score, DENSE_RANK() OVER (PARTITION BY CId ORDER BY score DESC) AS 'rank'
FROM SC;

16. 查询总成绩排名（保留空缺）

SELECT SId, total_score, RANK() OVER (ORDER BY total_score DESC) AS 'rank'
FROM (SELECT SId, SUM(score) AS total_score FROM SC GROUP BY SId
) t;

16.1 查询总成绩排名（不保留空缺）

SELECT SId, total_score, DENSE_RANK() OVER (ORDER BY total_score DESC) AS 'rank'
FROM (SELECT SId, SUM(score) AS total_score FROM SC GROUP BY SId
) t;

17. 统计各科成绩分数段人数及百分比

SELECT CId,SUM(CASE WHEN score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) AS "[85-100]",SUM(CASE WHEN score BETWEEN 70 AND 84 THEN 1 ELSE 0 END) AS "[70-84]",SUM(CASE WHEN score BETWEEN 60 AND 69 THEN 1 ELSE 0 END) AS "[60-69]",SUM(CASE WHEN score < 60 THEN 1 ELSE 0 END) AS "[0-59]",COUNT(*) AS total
FROM SC
GROUP BY CId;

18. 查询各科成绩前三名记录

SELECT * FROM (SELECT *, ROW_NUMBER() OVER (PARTITION BY CId ORDER BY score DESC) AS 'rank'FROM SC
) t WHERE rank <= 3;

19. 查询每门课程被选修的学生数

SELECT CId, COUNT(DISTINCT SId) AS student_count
FROM SC
GROUP BY CId;

20. 查询只选修两门课程的学生学号和姓名

SELECT s.SId, s.Sname
FROM Student s
JOIN SC sc ON s.SId = sc.SId
GROUP BY s.SId, s.Sname
HAVING COUNT(sc.CId) = 2;

21. 查询男生、女生人数

SELECT Ssex, COUNT(*) AS count FROM Student GROUP BY Ssex;

22. 查询名字含「风」的学生信息

SELECT * FROM Student WHERE Sname LIKE '%风%';

23. 查询同名同姓学生名单及统计

SELECT Sname, COUNT(*) AS count
FROM Student
GROUP BY Sname
HAVING COUNT(*) > 1;

24. 查询1990年出生的学生名单

SELECT * FROM Student WHERE YEAR(Sage) = 1990;

25. 按平均成绩降序排列课程

SELECT CId, AVG(score) AS avg_score
FROM SC
GROUP BY CId
ORDER BY avg_score DESC, CId;

26. 查询平均成绩大于等于85的学生信息

SELECT s.SId, s.Sname, AVG(sc.score) AS avg_score
FROM Student s
JOIN SC sc ON s.SId = sc.SId
GROUP BY s.SId, s.Sname
HAVING avg_score >= 85;

27. 查询数学课低于60分的学生及分数

SELECT s.Sname, sc.score
FROM Student s
JOIN SC sc ON s.SId = sc.SId
JOIN Course c ON sc.CId = c.CId
WHERE c.Cname = '数学' AND sc.score < 60;

28. 查询所有学生的课程及分数情况

SELECT s.SId, s.Sname, sc.CId, sc.score
FROM Student s
LEFT JOIN SC sc ON s.SId = sc.SId;

29. 查询任何课程成绩在70分以上的学生信息

SELECT DISTINCT s.Sname, c.Cname, sc.score
FROM Student s
JOIN SC sc ON s.SId = sc.SId
JOIN Course c ON sc.CId = c.CId
WHERE sc.score > 70;

30. 查询不及格的课程

SELECT DISTINCT CId FROM SC WHERE score < 60;

31. 查询课程01成绩80分以上的学生

SELECT s.SId, s.Sname
FROM Student s
JOIN SC sc ON s.SId = sc.SId
WHERE sc.CId = '01' AND sc.score >= 80;

32. 求每门课程的学生人数

SELECT CId, COUNT(DISTINCT SId) AS student_count
FROM SC
GROUP BY CId;

33. 查询张三老师课程成绩最高的学生信息

SELECT s.*, sc.score
FROM Student s
JOIN SC sc ON s.SId = sc.SId
JOIN Course c ON sc.CId = c.CId
JOIN Teacher t ON c.TId = t.TId
WHERE t.Tname = '张三'
ORDER BY sc.score DESC
LIMIT 1;

34. 成绩重复时查询最高分学生信息

SELECT s.*, sc.score
FROM Student s
JOIN SC sc ON s.SId = sc.SId
JOIN Course c ON sc.CId = c.CId
JOIN Teacher t ON c.TId = t.TId
WHERE t.Tname = '张三' AND sc.score = (SELECT MAX(score) FROM SCJOIN Course c ON SC.CId = c.CIdJOIN Teacher t ON c.TId = t.TIdWHERE t.Tname = '张三'
);

35. 查询不同课程成绩相同的学生

SELECT a.SId, a.CId, a.score
FROM SC a
JOIN SC b ON a.SId = b.SId AND a.CId != b.CId AND a.score = b.score;

36. 查询每门课程成绩最好的前两名

SELECT * FROM (SELECT *, ROW_NUMBER() OVER (PARTITION BY CId ORDER BY score DESC) AS `rank`FROM SC
) t WHERE `rank` <= 2;

37. 统计选修人数超过5人的课程

SELECT CId, COUNT(*) AS student_count
FROM SC
GROUP BY CId
HAVING student_count > 5;

38. 检索选修至少两门课程的学生学号

SELECT SId FROM SC
GROUP BY SId
HAVING COUNT(*) >= 2;

39. 查询选修了全部课程的学生信息

SELECT s.* FROM Student s
WHERE (SELECT COUNT(DISTINCT CId) FROM SC WHERE SId = s.SId) = (SELECT COUNT(*) FROM Course);

40. 按年份计算学生年龄

SELECT SId, Sname, YEAR(CURDATE()) - YEAR(Sage) AS age
FROM Student;

41. 精确计算年龄（考虑生日）

SELECT SId, Sname, TIMESTAMPDIFF(YEAR, Sage, CURDATE()) AS age
FROM Student;

42. 查询本周过生日的学生

SELECT * FROM Student
WHERE WEEKOFYEAR(Sage) = WEEKOFYEAR(CURDATE());

43. 查询下周过生日的学生

SELECT * FROM Student
WHERE WEEKOFYEAR(Sage) = WEEKOFYEAR(CURDATE()) + 1;

44. 查询本月过生日的学生

SELECT * FROM Student
WHERE MONTH(Sage) = MONTH(CURDATE());

45. 查询下月过生日的学生

SELECT * FROM Student
WHERE MONTH(Sage) = MONTH(CURDATE()) + 1;