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最全50个Mysql数据库查询练习题_Mysql_

2023-05-27 446人已围观

简介最全50个Mysql数据库查询练习题_Mysql_

此数据库查询语句是网络上50个数据库查询练习题目，网上有些版本是oracle语句写的，大多数公司还是用免费的mysql数据库，以下都是mysql版本，全部都有验证过。

表名和字段

–1.学生表
Student(s#, sname, sage,ssex) –学生编号,学生姓名, 出生年月,学生性别
–2.课程表
Course(c#,cname,t#) – –课程编号, 课程名称, 教师编号
–3.教师表
Teacher(t#,tname) –教师编号,教师姓名
–4.成绩表
Sc(s#,c#,score) –学生编号,课程编号,分数

测试数据

用数据库可视化工具做练习非常方便，推荐使用sqlyog，软件图标是一只海豚。

在新连接种填上本机地址，用户名，密码和端口就直接连上mysql。

所有测试数据如下：

 # --插入学生表测试数据 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' , '1990-05-20' , '男'); INSERT INTO student VALUES('04' , '李云' , '1990-08-06' , '男'); INSERT INTO student VALUES('05' , '周梅' , '1991-12-01' , '女'); INSERT INTO student VALUES('06' , '吴兰' , '1992-03-01' , '女'); INSERT INTO student VALUES('07' , '郑竹' , '1989-07-01' , '女'); INSERT INTO student VALUES('08' , '王菊' , '1990-01-20' , '女'); # --插入课程表测试数据 INSERT INTO course VALUES('01' , '语文' , '02'); INSERT INTO course VALUES('02' , '数学' , '01'); INSERT INTO course VALUES('03' , '英语' , '03'); # --插入教师表测试数据 INSERT INTO teacher VALUES('01' , '张三'); INSERT INTO teacher VALUES('02' , '李四'); INSERT INTO teacher VALUES('03' , '王五'); # --插入成绩表测试数据 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);

最后是50个数据库查询练习，已经验证过，是mysql版本的。

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 * FROM (SELECT `s#` AS sno1, `c#`AS cno1, score FROM sc WHERE `c#`=01) a LEFT JOIN (SELECT `s#` AS sno2, `c#`AS cno2, score FROM sc WHERE `c#`=02) b ON a.sno1 = b.sno2 WHERE a.score > b.score

1.1 查询同时存在" 01 "课程和" 02 "课程的情况

 SELECT * FROM (SELECT `s#` AS sno1, `c#`AS cno1, score FROM sc WHERE `c#`=01) a LEFT JOIN (SELECT `s#` AS sno2, `c#`AS cno2, score FROM sc WHERE `c#`=02) b ON a.sno1 = b.sno2 WHERE sno2 IS NOT NULL

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 * FROM (SELECT `s#` AS sno1, `c#`AS cno1, score FROM sc WHERE `c#`=01) a LEFT JOIN (SELECT `s#` AS sno2, `c#`AS cno2, score FROM sc WHERE `c#`=02) b ON a.sno1 = b.sno2

1.3 查询不存在" 01 "课程但存在" 02 "课程的情况

SELECT * FROM
sc WHERE `c#`='02' AND `s#` NOT IN (SELECT `s#` FROM sc WHERE `c#`='01')

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

 SELECT a.`s#`,b.`sname`, a.avg_score FROM (SELECT `s#` ,AVG(score) AS avg_score FROM sc GROUP BY `s#`) AS a LEFT JOIN student AS b ON a.`s#` = b.`s#` WHERE a.avg_score >=60

3. 查询在 SC 表存在成绩的学生信息

SELECT * FROM student WHERE `s#` IN (SELECT DISTINCT `s#` FROM sc)

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 )

 SELECT `s#` ,sname , course_num , score_sum FROM (SELECT `s#`, sname FROM student ) AS a LEFT JOIN (SELECT `s#` AS sno ,COUNT(`c#`) AS course_num ,SUM(score) AS score_sum FROM sc GROUP BY sno) AS b ON a.`s#` = b.sno

4.1 查有成绩的学生信息

# 在最外面一层select的时候，不可以用函数
# 如果两张表连接之后，有相同的字段，这时候select就需要把其中一个字段改名

 SELECT `s#` ,sname , course_num , score_sum FROM (SELECT `s#`, sname FROM student ) AS a LEFT JOIN (SELECT `s#` AS sno ,COUNT(`c#`) AS course_num ,SUM(score) AS score_sum FROM sc GROUP BY sno) AS b ON a.`s#` = b.sno WHERE course_num IS NOT NULL

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

 # 张三老师是01号 SELECT * FROM student WHERE `s#` IN (SELECT `s#` FROM sc WHERE `c#` = (SELECT `c#` FROM course WHERE `t#` = (SELECT `t#` FROM teacher WHERE tname='张三')))

# 7. 查询没有学全所有课程的同学的信息

SELECT `s#`,COUNT(`c#`) AS course_num FROM sc GROUP BY `s#`
HAVING course_num < (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 * FROM student WHERE `s#` IN (SELECT DISTINCT `s#` FROM sc WHERE `c#` IN (SELECT `c#` FROM sc WHERE `s#`=01)) AND `s#`!= 01

# 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

 SELECT `s#` FROM (SELECT * FROM sc LEFT JOIN (SELECT `c#` AS cno FROM sc WHERE `s#` =01) a ON sc.`c#` = a.cno) AS b GROUP BY `s#` HAVING COUNT(b.`s#`) = (SELECT COUNT(`c#`) AS cno FROM sc WHERE `s#` =01)

# 10. 查询没学过"张三"老师讲授的任一门课程的学生姓名

 # 张三是01 # 01老师是教数学，c#是02 SELECT * FROM student WHERE `s#` NOT IN (SELECT DISTINCT `s#` FROM sc WHERE `c#` IN (SELECT `c#` FROM course WHERE `t#` IN (SELECT `t#` FROM teacher WHERE tname = '张三')))

# 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

 SELECT `s#`, sname, avg_score FROM (SELECT `s#`, sname FROM student WHERE `s#` IN (SELECT a.`s#` FROM (SELECT `s#`,COUNT(`c#`) AS num FROM sc WHERE score <60 GROUP BY `s#`) a WHERE num >=2)) AS b LEFT JOIN (SELECT `s#` AS sno ,AVG(score) AS avg_score FROM sc GROUP BY `s#`) AS c ON b.`s#` = c.sno

# 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#`, sname, score FROM student AS a LEFT JOIN (SELECT `s#` AS sno,`c#`,score FROM sc WHERE `c#`= 01 AND score <60 )b ON a.`s#`= b.sno WHERE score IS NOT NULL ORDER BY score DESC

# 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

SELECT `s#` ,AVG(score) AS avg_score FROM sc GROUP BY `s#` ORDER BY avg_score DESC

# 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

 SELECT DISTINCT a.`c#`,cname,最高分,最低分,平均分,及格率,中等率,优良率,优秀率 FROM sc a LEFT JOIN course ON a.`c#`=course.`c#` LEFT JOIN (SELECT `c#`, MAX(score)最高分, MIN(score)最低分, AVG(score)平均分 FROM sc GROUP BY `c#`)b ON a.`c#`=b.`c#` LEFT JOIN (SELECT `c#`, ROUND( r1 /cnt * 100, 2 ) AS 及格率 FROM (SELECT `c#`, (SUM(CASE WHEN score >=60 THEN 1 ELSE 0 END)*1.00) AS r1 , COUNT(*) AS cnt FROM sc GROUP BY `c#`) c1) c ON a.`c#`=c.`c#` LEFT JOIN (SELECT `c#`, ROUND( r2 /cnt * 100, 2 ) AS 中等率 FROM (SELECT `c#`, (SUM(CASE WHEN score >=70 AND score<80 THEN 1 ELSE 0 END)*1.00) AS r2 , COUNT(*) AS cnt FROM sc GROUP BY `c#`) d1) d ON a.`c#`=d.`c#` LEFT JOIN (SELECT `c#`, ROUND( r3 /cnt * 100, 2 ) AS 优良率 FROM (SELECT `c#`, (SUM(CASE WHEN score >=80 AND score<90 THEN 1 ELSE 0 END)*1.00) AS r3 , COUNT(*) AS cnt FROM sc GROUP BY `c#`) e1) e ON a.`c#`=e.`c#` LEFT JOIN (SELECT `c#`, ROUND( r4 /cnt * 100, 2 ) AS 优秀率 FROM (SELECT `c#`, (SUM(CASE WHEN score >=90 THEN 1 ELSE 0 END)*1.00) AS r4 , COUNT(*) AS cnt FROM sc GROUP BY `c#`) f1) f ON a.`c#`=f.`c#`

# 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

 # mysql中没有rank()函数 # 这种是重复时候保留名次，所以最后名次和人数是一样的 SELECT `s#`, `c#`, score, rank FROM (SELECT `s#`, `c#`, score, @currank := IF(@prevrank = score, @currank, @incrank) AS rank, @incrank := @incrank + 1, @prevrank := score FROM sc , ( SELECT @currank :=0, @prevrank := NULL, @incrank := 1 ) r ORDER BY score DESC) s

# 15.1 按各科成绩进行排序，并显示排名， Score 重复时合并名次

 # 这种是当有重复名次的时候变成只有一个名次，所以排名的数量会变少 SELECT `s#`, `c#`, score, CASE WHEN @prevrank = score THEN @currank WHEN @prevrank := score THEN @currank := @currank + 1 END AS rank FROM sc, (SELECT @currank :=0, @prevrank := NULL) r ORDER BY score DESC

# 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

 # from后面不需要加表的别名 SELECT `s#`, sum_score, rank FROM (SELECT `s#`, sum_score, @currank := IF(@prevrank = sum_score, @currank, @incrank) AS rank, @incrank := @incrank + 1, @prevrank := sum_score FROM (SELECT `s#`, SUM(score) AS sum_score FROM sc GROUP BY `s#`) c , (SELECT @currank :=0, @prevrank := NULL, @incrank := 1) r ORDER BY sum_score DESC) s

# 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

 SELECT c.*, CASE WHE
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最全50个Mysql数据库查询练习题_Mysql_

表名和字段

测试数据

所有测试数据如下：

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