Mysql 练习题 及 答案
mysql 答案 练习题
2023-06-13 09:11:13 时间
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–1.学生表 Student(S,Sname,Sage,Ssex) –S 学生编号,Sname 学生姓名,Sage 出生年月,Ssex 学生性别 –2.课程表 Course(C,Cname,T) –C —课程编号,Cname 课程名称,T 教师编号 –3.教师表 Teacher(T,Tname) –T 教师编号,Tname 教师姓名 –4.成绩表 SC(S,C,score) –S 学生编号,C 课程编号,score 分数
--创建测试数据
create table Student(
S varchar(10),
Sname varchar(10),
Sage datetime,
Ssex nvarchar(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' , '1990-05-20' , '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');
create table SC(
S varchar(10),
C 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);create table Course(
C varchar(10),
Cname varchar(10),
T 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');
create table Teacher(
T 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');–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 a.*
,b.score AS '01分数'
,c.score AS '02分数'
FROM student a
INNER JOIN sc b
ON a.s=b.s AND b.c='01'
INNER JOIN sc c
ON a.s=c.s AND c.c='02'
WHERE b.score > c.score ;–2、查询“01”课程比“02”课程成绩低的学生的信息及课程分数 –3、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
,a.sname
,AVG(b.score) AS avgnum
FROM student a
INNER JOIN sc b
ON a.s=b.s
GROUP BY a.s,a.sname
HAVING AVG(b.score)>60 ;–4、查询平均成绩小于60分的同学的学生编号和学生姓名和平均成绩 –5、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
–6、查询“李“姓老师的数量
SELECT COUNT(1) FROM teacherWHERE tname LIKE '李%' ;–7、查询学过“张三“老师授课的同学的信息
SELECT a.*
FROM student a
INNER JOIN sc b
ON a.s=b.s
INNER JOIN course c
ON b.c=c.c
INNER JOIN teacher d
ON c.t=d.t
WHERE d.tname='张三'
GROUP BY 1,2,3,4 ;
--方法2
SELECT a.*
FROM student a
LEFT JOIN (
SELECT a.*
FROM student a
INNER JOIN sc b
ON a.s=b.s
INNER JOIN course c
ON b.c=c.c
INNER JOIN teacher d
ON c.t=d.t
WHERE d.tname='张三'
GROUP BY 1,2,3,4
)b
ON a.s=b.s
WHERE b.s IS NOT NULL ;–8、查询没学过“张三“老师授课的同学的信息
SELECT a.*
FROM student a
LEFT JOIN sc b
ON a.s=b.s
WHERE NOT EXISTS(
SELECT *
FROM course aa
INNER JOIN teacher b
ON aa.t=b.t
INNER JOIN sc c
ON aa.c=c.c
WHERE b.tname='张三'
AND c.s=a.s
)
GROUP BY 1,2,3,4 ;–9、查询学过编号为“01”并且也学过编号为“02”的课程的同学的信息
SELECT a.*
FROM student a
INNER JOIN sc b
ON a.s=b.s AND b.c='01'
INNER JOIN sc c
ON a.s=c.s AND c.c='02' ;–10、查询学过编号为“01”但是没有学过编号为“02”的课程的同学的信息
select *
from student a
left join sc b
on a.s=b.s and b.c='01'
left join sc c
on a.s=c.s and c.c='02'
where b.c='01' and c.c is null ;–11、查询没有学全所有课程的同学的信息
SELECT a.*
FROM student a
LEFT JOIN sc b
ON a.s=b.s
LEFT JOIN (SELECT COUNT(1) anumFROM course) c
ON 1=1
GROUP BY 1,2,3,4
HAVING MAX(c.anum)>COUNT(b.c) ;–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 a.*
FROM student a
INNER JOIN sc b
ON a.s=b.s
WHERE EXISTS(
SELECT 1 FROM sc WHERE s='01' AND c=b.c
)
GROUP BY 1,2,3,4 ;–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 a.s,a.sname,a.sage,a.ssex
FROM (SELECT a.*,COUNT(b.c) ASsnum
FROM student a
INNER JOIN sc b
ON a.s=b.s
WHERE EXISTS(
SELECT 1 FROM scWHERE s='01' AND c=b.c
)
GROUP BY 1,2,3,4)a
INNER JOIN (SELECTa.*,COUNT(b.c) AS anum
FROM student a
INNER JOIN sc b
ON a.s=b.s
GROUP BY 1,2,3,4)b
ON a.s=b.s
INNER JOIN (SELECT COUNT(1) ASnum1 FROM sc WHERE s='01')c
ON 1=1
WHERE a.snum=b.anum ANDa.snum=c.num1 ;
--方法二
SELECT a.*
,COUNT(b.c) AS anum
,SUM(CASE WHEN EXISTS(SELECT 1 FROM sc WHERE s='01' AND c=b.c)THEN 1 ELSE 0 END) AS snum
,MAX(c.num1) AS num1
FROM student a
INNER JOIN sc b
ON a.s=b.s
INNER JOIN (SELECT COUNT(1) ASnum1 FROM sc WHERE s='01')c
ON 1=1
GROUP BY 1,2,3,4
HAVING anum=snum AND anum=num1 ;–14、查询没学过“张三“老师讲授的任一门课程的学生姓名
SELECT a.*
FROM student a
LEFT JOIN(
SELECT a.s
FROM student a
LEFT JOIN sc b
ON a.s=b.s
LEFT JOIN course c
ON b.c=c.c
LEFT JOIN teacher d
ON c.t=d.t AND d.tname='张三'
WHERE d.t IS NOT NULL
)b
ON a.s=b.s
WHERE b.s IS NULL ;–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 a.s
,a.sname
,AVG(b.score)
FROM student a
INNER JOIN sc b
ON a.s=b.s
GROUP BY 1,2
HAVING SUM(CASE WHENb.score>=60 THEN 0 ELSE 1 END)>=2 ;–16、检索“01”课程分数小于60，按分数降序排列的学生信息
SELECT a.*
,b.score
FROM student a
INNER JOIN sc b
ON a.s=b.s
WHERE
b.c='01'
AND b.score < 60
ORDER BY b.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 a.*
,SUM(CASE WHEN b.c='01' THEN b.scoreELSE 0 END) AS s01
,SUM(CASE WHEN b.c='02' THEN b.scoreELSE 0 END) AS s02
,SUM(CASE WHEN b.c='03' THEN b.score ELSE0 END) AS s03
,AVG(CASE WHEN b.score IS NULL THEN 0 ELSE b.score END) avs
FROM student a
LEFT JOIN sc b
ON a.s=b.s
GROUP BY 1,2,3,4
ORDER BY avs 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
SELECT a.c
,a.cname
,MAX(b.score)
,MIN(b.score)
,AVG(b.score)
,SUM(CASE WHEN b.score>=60 THEN 1 ELSE 0 END)/COUNT(1)
,SUM(CASE WHEN b.score>=70 AND b.score<80 THEN 1 ELSE 0 END)/COUNT(1)
,SUM(CASE WHEN b.score>=80 AND b.score<90 THEN 1 ELSE 0 END)/COUNT(1)
,SUM(CASE WHEN b.score>=90 THEN 1 ELSE 0 END)/COUNT(1)
FROM course a
INNER JOIN sc b
ON a.c=b.c
GROUP BY 1,2 ;–19、按各科成绩进行排序，并显示排名
SET @rn:=0;
SELECT a.*,@rn:=@rn+1
FROM(
SELECT a.*,b.score
FROM course a
INNER JOIN sc b
ON a.c=b.c
WHERE a.c='01'
ORDER BY b.c,score DESC
)a ;–20、查询学生的总成绩并进行排名
SELECT a.*
,COUNT(b.c)+1 asall
FROM sc a
LEFT JOIN sc b
ON a.c=b.c AND a.score < b.score
GROUP BY 1,2,3
ORDER BY a.c,asall ;–21、查询不同老师所教不同课程平均分从高到低显示
SELECT a.*
,b.cname
,AVG(c.score) ascore
FROM teacher a
INNER JOIN course b
ON a.t=b.t
INNER JOIN sc c
ON b.c=c.c
GROUP BY 1,2,3
ORDER BY ascore DESC ;–22、查询所有课程的成绩第2名到第3名的学生信息及该课程成绩
SELECT a.*,b.cname,b.score
FROM student a
INNER JOIN (
SELECT a.*
,c.cname
,COUNT(b.c)+1 AStp
FROM sc a
LEFT JOIN sc b
ON a.c=b.c AND a.score<b.score
LEFT JOIN course c
ON a.c=c.c
GROUP BY 1,2,3,4
HAVING COUNT(b.c)+1 IN(2,3)
ORDER BY a.c,tp)b
ON a.s=b.s ;–23、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],[0-60]及所占百分比
SELECT a.c
,a.cname
,SUM(CASE WHEN b.score<=100 AND b.score>85 THEN 1 ELSE 0 END) AS '[100-85]'
,SUM(CASE WHEN b.score<=85 AND b.score>70 THEN 1 ELSE 0 END) AS '[85-70]'
,SUM(CASE WHEN b.score<=70 AND b.score>60 THEN 1 ELSE 0 END) AS '[70-60]'
,SUM(CASE WHEN b.score<=60 AND b.score>0 THEN 1 ELSE 0 END) AS '[60-0]'
,SUM(CASE WHEN b.score<=100 AND b.score>85 THEN 1 ELSE 0 END)/COUNT(1) AS '[100-85]%'
,SUM(CASE WHEN b.score<=85 AND b.score>70 THEN 1 ELSE 0 END)/COUNT(1) AS '[85-70]%'
,SUM(CASE WHEN b.score<=70 AND b.score>60 THEN 1 ELSE 0 END)/COUNT(1) AS '[70-60]%'
,SUM(CASE WHEN b.score<=60 AND b.score>0 THEN 1 ELSE 0 END)/COUNT(1) AS '[60-0]%'
FROM course a
INNER JOIN sc b
ON a.c=b.c
GROUP BY 1,2 ;–24、查询学生平均成绩及其名次
SELECT a.*
,COUNT(b.s)+1
FROM (
SELECT a.*,AVG(CASE WHEN b.score IS NULL THEN 0 ELSE b.scoreEND) AS ascore
FROM student a
LEFT JOIN sc b
ON a.s=b.s
GROUP BY 1,2,3,4
)a
LEFT JOIN(
SELECT a.*,AVG(CASE WHEN b.score IS NULL THEN 0 ELSE b.scoreEND) AS ascore
FROM student a
LEFT JOIN sc b
ON a.s=b.s
GROUP BY 1,2,3,4
)b
ON a.ascore<b.ascore
GROUP BY 1,2,3,4,5 ;–25、查询各科成绩前三名的记录
SELECT a.*,COUNT(b.c)+1 ASascore
FROM sc a
LEFT JOIN sc b
ON a.c=b.c AND a.score<b.score
GROUP BY 1,2,3
HAVING ascore<=3
ORDER BY a.c,ascore ;–26、查询每门课程被选修的学生数
SELECT a.*
,COUNT(b.s)
FROM course a
LEFT JOIN sc b
ON a.c=b.c
GROUP BY 1,2,3 ;–27、查询出只有两门课程的全部学生的学号和姓名
SELECT a.*
,COUNT(b.c)
FROM student a
LEFT JOIN sc b
ON a.s=b.s
GROUP BY 1,2,3,4
HAVING COUNT(b.c)=2 ;–28、查询男生、女生人数 –29、查询名字中含有“风“字的学生信息 –30、查询同名同性学生名单，并统计同名人数
SELECT sname
,ssex
,COUNT(1)
FROM student
GROUP BY 1,2
HAVING COUNT(1) > 1 ;–31、查询1990年出生的学生名单(注：Student表中Sage列的类型是datetime)
SELECT * FROM student WHERE YEAR(sage)=1990 ;–32、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
SELECT a.*
,AVG(b.score) ascore
FROM course a
LEFT JOIN sc b
ON a.c=b.c
GROUP BY 1,2,3
ORDER BYascore DESC,a.c ;–33、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 a.*
,AVG(b.score) ascore
FROM student a
LEFT JOIN sc b
ON a.s=b.s
GROUP BY 1,2,3,4
HAVING ascore>=85 ;–34、查询课程名称为“数学“，且分数低于60的学生姓名和分数
SELECT c.*
FROM course a
LEFT JOIN sc b
ON a.c=b.c
LEFT JOIN student c
ON b.s=c.s
WHERE a.cname='数学'
AND b.score < 60 ;–35、查询所有学生的课程及分数情况；
SELECT *
FROM sc a
INNER JOIN student b
ON a.s=b.s
INNER JOIN course c
ON a.c=c.c ;–36、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 b.sname
,c.cname
,a.score
FROM sc a
INNER JOIN student b
ON a.s=b.s
INNER JOIN course c
ON a.c=c.c
WHERE a.score > 70 ;–37、查询不及格的课程 –38、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 a.*
FROM student a
INNER JOIN sc b
ON a.s=b.s
WHERE b.c='01' AND b.score > 80 ;–39、求每门课程的学生人数 –40、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 a.*,b.score
FROM student a
INNER JOIN sc b
ON a.s=b.s
INNER JOIN(
SELECT c.c
,MAX(c.score) ASmaxscore
FROM teacher a
INNER JOIN course b
ON a.t=b.t
INNER JOIN sc c
ON b.c=c.c
WHERE a.tname='张三'
GROUP BY c)c
ON b.c=c.c AND b.score=c.maxscore ;–41、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.s
,a.c
,a.score
FROM sc a
INNER JOIN (
SELECT a.score
,b.s
,COUNT(1)
FROM sc a
INNER JOIN student b
ON a.s=b.s
GROUP BY a.score,b.s
HAVING COUNT(1)>1
)b
ON a.s=b.s AND a.score=b.score ;
方法二
SELECT a.*
FROM sc a
LEFT JOIN sc b
ON a.s=b.s AND a.score=b.score AND a.c <> b.c
GROUP BY 1,2,3
HAVING COUNT(b.s) > 0 ;–42、查询每门功成绩最好的前两名 –43、统计每门课程的学生选修人数（超过5人的课程才统计）。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 a.c
,COUNT(1) AS pnum
FROM sc a
GROUP BY 1
HAVING pnum > 5
ORDER BY pnum DESC,a.c ;–44、检索至少选修两门课程的学生学号 –45、查询选修了全部课程的学生信息
–46、查询各学生的年龄
SELECT a.*,YEAR(CURDATE())-YEAR(a.sage)
FROM student a ;–47、查询本周过生日的学生
SELECT a.*
FROM student a
WHERE CONCAT(MONTH(a.sage),DAY(a.sage))>=CONCAT(MONTH(SUBDATE(CURDATE(),WEEKDAY(CURDATE()))),DAY(SUBDATE(CURDATE(),WEEKDAY(CURDATE()))))
AND CONCAT(MONTH(a.sage),DAY(a.sage))<=CONCAT(MONTH(SUBDATE(CURDATE(),WEEKDAY(CURDATE())-6)),DAY(SUBDATE(CURDATE(),WEEKDAY(CURDATE())-6))) ;–48、查询下周过生日的学生
–49、查询本月过生日的学生
SELECT a.* FROM student a WHERE MONTH(a.sage)=MONTH(CURDATE()) ;–50、查询下月过生日的学生
SELECT a.*FROM student a WHERE MONTH(a.sage)=MONTH(CURDATE())+1 ;有些没有答案的，是因为和上面的差不多，偷个懒。。。。
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