sql之sql经典45题_mysql
sql之mysql45题
- 建表+数据
- 建表语句
- 增加数据
- 45题
- 个人认为第11,12,13,18,20,26,38,42题比较有意思
- 1.查询“001”课程比“002”课程成绩高的所有学生的学号;
- 2.查询平均成绩大于60分的同学的学号和平均成绩;
- 3.查询所有同学的学号、姓名、选课数、总成绩;
- 4.查询姓“李”的老师的个数;
- 5.查询没学过“叶平”老师课的同学的学号、姓名;
- 6.查询学过“001”并且也学过编号“002”课程的同学的学号、姓名;
- 7.查询学过“叶平”老师所教的所有课的同学的学号、姓名;
- 8.查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名;
- 9.查询所有课程成绩小于60分的同学的学号、姓名;
- 9.1、
- 9.2、一个课程都没有选择的也算是成绩在60以下
- 10.查询没有学全所有课的同学的学号、姓名;
- 11.****查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名; ****
- 12.****把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩;****
- 13.****查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名; ****
- 方法1：
- 方法2：
- 13扩展、查询所有包含“1002”号的同学学习的所有课程的其他同学学号和姓名;
- 14.删除学习“叶平”老师课的SC表记录;
- 15.按平均成绩从高到低显示所有学生的“数据库”、“企业管理”、“英语”三门的课程成绩，按如下形式显示： 学生ID,,数据库,企业管理,英语,有效课程数,有效平均分
- 16.查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分
- 17.按各科平均成绩从低到高和及格率的百分数从高到低排序
- 17.1.测试：中文升序降序不好使
- 17.2.别名改为英文才可以
- 18.****查询如下课程平均成绩和及格率的百分数(用1行显示): 企业管理（001），马克思（002），UML （003），数据库（004） ****
- 19.查询不同老师所教不同课程平均分从高到低显示 要求显示：教师ID,教师姓名，课程ID,课程名称，平均成绩
- 20.****统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ <60] （从本题开始没有使用美化sql）****
- 20.1.使用大于小于号
- 20.2.使用BETWEEN-AND
- 21.查询每门课程被选修的学生数
- 22.查询出只选修了一门课程的全部学生的学号和姓名
- 23.查询男生、女生人数
- 24.查询姓“张”的学生名单
- 25.查询同名同性学生名单，并统计同名人数
- 26.****1981年出生的学生名单(注：Student表中Sage列的类型是datetime)****
- 27.查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列
- 28.查询平均成绩大于85的所有学生的学号、姓名和平均成绩
- 29.查询课程名称为“数据库”，且分数低于60的学生姓名和分数
- 30.查询所有学生的选课情况;
- 31.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;
- 32.查询不及格的课程，并按课程号从大到小排列
- 33.查询课程编号为003且课程成绩在80分以上的学生的学号和姓名;
- 34.求选了课程的学生人数
- 34.1统计sc表的总数
- 34.2在sid上去重
- 35.查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩
- 36.查询各个课程及相应的选修人数
- 37.查询不同课程成绩相同的学生的学号、课程号、学生成绩
- 38.****查询每门功课成绩最好的前两名****
- 38.1如果第二名和之后学生的成绩相同，则舍去
- 38.2如果第二名和之后学生的成绩相同，则都显示
- 39.统计每门课程的学生选修人数。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
- 40.检索至少选修两门课程的学生学号
- 41.查询全部学生都选修的课程的课程号和课程名
- 42.****查询没学过“叶平”老师讲授的任一门课程的学生姓名 ****
- 43.查询两门以上不及格课程的同学的学号及其平均成绩
- 44.检索“004”课程分数小于60，按分数降序排列的同学学号
- 45.删除“1002”同学的“001”课程的成绩
- 金融理财师（AFP）双证
建表+数据
建表语句
/*Student(sid,Sname,Sage,Ssex) 学生表*/
CREATE TABLE student (
sid varchar(10) NOT NULL,
sName varchar(20) DEFAULT NULL,
sAge datetime DEFAULT '1980-10-12 23:12:36',
sSex varchar(10) DEFAULT NULL,
PRIMARY KEY (sid)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
/*Course(cid,Cname,tid) 课程表 */
CREATE TABLE course (
cid varchar(10) NOT NULL,
cName varchar(10) DEFAULT NULL,
tid int(20) DEFAULT NULL,
PRIMARY KEY (cid)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
/*SC(sid,cid,score) 成绩表 */
CREATE TABLE sc (
sid varchar(10) DEFAULT NULL,
cid varchar(10) DEFAULT NULL,
score int(10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
/*Teacher(tid,Tname) 教师表*/
CREATE TABLE teacher (
tid int(10) DEFAULT NULL,
tName varchar(10) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
增加数据
/*增加数据*/
insert into teacher(tid,tName) values (1,'李老师'),(2,'何以琛'),(3,'叶平');
insert into student(sid,sName,sAge,sSex) values ('1001','张三丰','1980-10-12 23:12:36','男'),('1002','张无极','1995-10-12 23:12:36','男'),('1003','李奎','1992-10-12 23:12:36','女'),('1004','李元宝','1980-10-12 23:12:36','女'),('1005','李世明','1981-10-12 23:12:36','男'),('1006','赵六','1986-10-12 23:12:36','男'),('1007','田七','1981-10-12 23:12:36','女');
insert into sc(sid,cid,score) values ('1001','001',80),('1001','002',60),('1001','003',75),('1002','001',85),('1002','002',70),('1003','004',100),('1003','001',90),('1003','002',55),('1004','002',65),('1004','003',60);
insert into course(cid,cName,tid) values ('001','企业管理',3),('002','马克思',3),('003','UML',2),('004','数据库',1),('005','英语',1);
45题
个人认为第11,12,13,18,20,26,38,42题比较有意思
1.查询“001”课程比“002”课程成绩高的所有学生的学号;
SELECT
a.sid
FROM
(
SELECT
sid,
score
FROM
sc
WHERE
cid = '001'
) a
LEFT JOIN (
SELECT
sid,
score
FROM
sc
WHERE
cid = '002'
) b ON a.sid = b.sid
WHERE
a.score > b.score
2.查询平均成绩大于60分的同学的学号和平均成绩;
SELECT
sid,
AVG(score) score
FROM
sc
GROUP BY
sid
HAVING
AVG(score) > 60;
3.查询所有同学的学号、姓名、选课数、总成绩;
SELECT
student.sid,
MAX(student.sName),
COUNT(sc.cid) cidnum,
SUM(sc.score) score
FROM
student
LEFT JOIN sc ON student.sid = sc.sid
GROUP BY
student.sid
4.查询姓“李”的老师的个数;
SELECT
SUM(teacher.tid)
FROM
teacher
WHERE
teacher.tName LIKE '李%';
5.查询没学过“叶平”老师课的同学的学号、姓名;
select s.sid,s.sName from student s where s.sid
NOT IN (
select stu.sid from student stu
LEFT JOIN sc on sc.sid = stu.sid
LEFT JOIN course on course.cid = sc.cid
LEFT JOIN teacher on teacher.tid = course.tid
WHERE teacher.tName = '叶平'
)
6.查询学过“001”并且也学过编号“002”课程的同学的学号、姓名;
SELECT
a.sid
FROM
(
SELECT
sid,
score
FROM
sc
WHERE
cid = '001'
) a
LEFT JOIN (
SELECT
sid,
score
FROM
sc
WHERE
cid = '002'
) b ON a.sid = b.sid
7.查询学过“叶平”老师所教的所有课的同学的学号、姓名;
SELECT
s.sid,
s.sName
FROM
student s
WHERE
s.sid IN (
SELECT
stu.sid
FROM
student stu
LEFT JOIN sc ON sc.sid = stu.sid
LEFT JOIN course ON course.cid = sc.cid
LEFT JOIN teacher ON teacher.tid = course.tid
WHERE
teacher.tName = '叶平'
GROUP BY
stu.sid
HAVING
COUNT(stu.sid) = (
SELECT
COUNT(teacher.tid)
FROM
teacher
LEFT JOIN course ON teacher.tid = course.tid
WHERE
teacher.tName = '叶平'
)
)
8.查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名;
SELECT
student.sid,
student.sName
FROM
(
SELECT
sid,
score
FROM
sc
WHERE
cid = '001'
) a
LEFT JOIN (
SELECT
sid,
score
FROM
sc
WHERE
cid = '002'
) b ON a.sid = b.sid
LEFT JOIN student ON b.sid = student.sid
WHERE
a.score > b.score
9.查询所有课程成绩小于60分的同学的学号、姓名;
9.1、
SELECT
student.sid,
student.sName
FROM
(
SELECT
sid,
score
FROM
sc
WHERE
cid = '001'
) a
LEFT JOIN (
SELECT
sid,
score
FROM
sc
WHERE
cid = '002'
) b ON a.sid = b.sid
LEFT JOIN (
SELECT
sid,
score
FROM
sc
WHERE
cid = '002'
) c ON c.sid = b.sid
LEFT JOIN student ON c.sid = student.sid
WHERE
a.score < 60
AND b.score < 60
AND c.score < 60
9.2、一个课程都没有选择的也算是成绩在60以下
select sid,Sname
from Student
where sid not in (select Student.sid from Student,SC where Student.sid=SC.sid and score>60);
10.查询没有学全所有课的同学的学号、姓名;
select sid,Sname
from Student
where sid not in (select Student.sid from Student,SC where Student.sid=SC.sid);
11.****查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名; ****
SELECT
student.sid,
student.sName
FROM
student
LEFT JOIN sc ON sc.sid = student.sid
WHERE
sc.cid IN (
SELECT
sc.cid
FROM
sc
WHERE
sc.sid = '1001'
)
AND sc.sid != '1001'
GROUP BY
student.sid
12.把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩;
UPDATE sc,
(
SELECT
c.cid,
AVG(score) avgs
FROM
sc,
course c,
teacher t
WHERE
sc.cid = c.cid
AND c.tid = t.tid
AND t.tName = '叶平'
GROUP BY
c.cid
) sc_2
SET sc.score = sc_2.avgs
WHERE
sc.cid = sc_2.cid
13.****查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名; ****
课程完全相同:两个人的课程一模一样，谁的都不能多，也不能少
其他同学:搜索的结果不能为1002号同学
方法1：
SELECT
SC.sid
FROM
SC
LEFT JOIN (
SELECT
sid,
count(1) a1
FROM
SC
GROUP BY
sid
) a ON SC.sid = a.sid
LEFT JOIN (
SELECT
count(1) b1
FROM
SC
WHERE
sid = '1002'
) b ON a.a1 = b.b1
WHERE
cid IN (
SELECT
cid
FROM
SC
WHERE
sid = '1002'
)
AND a.a1 = b.b1
AND SC.sid != '1002'
GROUP BY
sid
方法2：
SELECT
SC.sid
FROM
SC
LEFT JOIN (
SELECT
sid,
count(1) a1
FROM
SC
GROUP BY
sid
) a ON SC.sid = a.sid
WHERE
cid IN (
SELECT
cid
FROM
SC
WHERE
sid = '1002'
)
AND a.a1 = (
SELECT
count(1) b1
FROM
SC
WHERE
sid = '1002'
)
AND SC.sid != '1002'
GROUP BY
sid
13扩展、查询所有包含“1002”号的同学学习的所有课程的其他同学学号和姓名;
SELECT
sid,
count(1)
FROM
SC
WHERE
cid IN (
SELECT
cid
FROM
SC
WHERE
sid = '1002'
)
GROUP BY
sid
HAVING
count(1) = (
SELECT
count(1)
FROM
SC
WHERE
sid = '1002'
);
14.删除学习“叶平”老师课的SC表记录;
DELETE
FROM
sc
WHERE
cid IN (
SELECT
cid
FROM
course
LEFT JOIN teacher ON course.tid = teacher.tid
WHERE
teacher.tName = '叶平'
);
15.按平均成绩从高到低显示所有学生的“数据库”、“企业管理”、“英语”三门的课程成绩，按如下形式显示： 学生ID,数据库,企业管理,英语,有效课程数,有效平均分
SELECT
sid AS 学生ID,
(
SELECT
score
FROM
SC
WHERE
SC.sid = t.sid
AND cid = '004'
) AS 数据库,
(
SELECT
score
FROM
SC
WHERE
SC.sid = t.sid
AND cid = '001'
) AS 企业管理,
(
SELECT
score
FROM
SC
WHERE
SC.sid = t.sid
AND cid = '005'
) AS 英语,
COUNT(*) AS 有效课程数,
AVG(t.score) AS 平均成绩
FROM
SC AS t
GROUP BY
sid
ORDER BY
avg(t.score)
16.查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分
SELECT
cid '课程ID',
MAX(score) '最高分',
MIN(score) '最低分'
FROM
sc
GROUP BY
cid
17.按各科平均成绩从低到高和及格率的百分数从高到低排序
17.1.测试：中文升序降序不好使
SELECT
cid '课程ID',
AVG(score) '平均成绩',
SUM(
CASE
WHEN IFNULL(score, 0) > 60 THEN
1
ELSE
0
END
) / COUNT(1) '及格率'
FROM
sc
GROUP BY
cid
ORDER BY
'平均成绩' DESC,
'及格率' DESC
17.2.别名改为英文才可以
SELECT
cid '课程ID',
AVG(score) avg_s,
SUM(
CASE
WHEN IFNULL(score, 0) > 60 THEN
1
ELSE
0
END
) / COUNT(1) pass_rate
FROM
sc
GROUP BY
cid
ORDER BY
avg_s DESC,
pass_rate DESC
18.****查询如下课程平均成绩和及格率的百分数(用1行显示): 企业管理（001），马克思（002），UML （003），数据库（004） ****
SELECT
SUM(
CASE
WHEN cid = '001' THEN
IFNULL(score, 0)
ELSE
0
END
) / SUM(
CASE
WHEN cid = '001' THEN
1
ELSE
0
END
) '企业管理平均成绩',
SUM(
CASE
WHEN IFNULL(score, 0) > 60
AND cid = '001' THEN
1
ELSE
0
END
) / SUM(
CASE
WHEN cid = '001' THEN
1
ELSE
0
END
) * 100 '企业管理百分比',
SUM(
CASE
WHEN cid = '002' THEN
IFNULL(score, 0)
ELSE
0
END
) / SUM(
CASE
WHEN cid = '002' THEN
1
ELSE
0
END
) '马克思平均成绩',
SUM(
CASE
WHEN IFNULL(score, 0) > 60
AND cid = '002' THEN
1
ELSE
0
END
) / SUM(
CASE
WHEN cid = '002' THEN
1
ELSE
0
END
) * 100 '马克思百分比',
SUM(
CASE
WHEN cid = '003' THEN
IFNULL(score, 0)
ELSE
0
END
) / SUM(
CASE
WHEN cid = '003' THEN
1
ELSE
0
END
) 'UML平均成绩',
SUM(
CASE
WHEN IFNULL(score, 0) > 60
AND cid = '003' THEN
1
ELSE
0
END
) / SUM(
CASE
WHEN cid = '003' THEN
1
ELSE
0
END
) * 100 'UML百分比',
SUM(
CASE
WHEN cid = '004' THEN
IFNULL(score, 0)
ELSE
0
END
) / SUM(
CASE
WHEN cid = '004' THEN
1
ELSE
0
END
) '数据库平均成绩',
SUM(
CASE
WHEN IFNULL(score, 0) > 60
AND cid = '004' THEN
1
ELSE
0
END
) / SUM(
CASE
WHEN cid = '004' THEN
1
ELSE
0
END
) * 100 '数据库百分比'
FROM
sc
19.查询不同老师所教不同课程平均分从高到低显示 要求显示：教师ID,教师姓名，课程ID,课程名称，平均成绩
SELECT
MAX(t.tid),
MAX(t.tName),
c.cid,
MAX(c.cName),
AVG(score)
FROM
teacher t
LEFT JOIN course c ON t.tid = c.tid
LEFT JOIN sc ON sc.cid = c.cid
GROUP BY
c.cid
20.统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ <60] （从本题开始没有使用美化sql）
20.1.使用大于小于号
SELECT
sc.cid,MAX(cName) '课程名称',
SUM(CASE WHEN score >= 85 THEN 1 ELSE 0 END) '[100-85]',
SUM(CASE WHEN score >= 70 AND score < 85 THEN 1 ELSE 0 END) '[70-85]',
SUM(CASE WHEN score < 70 AND score >= 60 THEN 1 ELSE 0 END) '[60-70]',
SUM(CASE WHEN score < 60 THEN 1 ELSE 0 END) '[60-0]'
FROM
sc LEFT JOIN course on sc.cid = course.cid
GROUP BY sc.cid
20.2.使用BETWEEN-AND
SELECT SC.cid as 课程ID, Cname as 课程名称
,SUM(CASE WHEN score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) AS '[100 - 85]'
,SUM(CASE WHEN score BETWEEN 70 AND 84 THEN 1 ELSE 0 END) AS '[85 - 70]'
,SUM(CASE WHEN score BETWEEN 60 AND 69 THEN 1 ELSE 0 END) AS '[70 - 60] '
,SUM(CASE WHEN score < 60 THEN 1 ELSE 0 END) AS '[60 -] '
FROM SC,Course
where SC.cid=Course.cid
GROUP BY SC.cid,Cname;
21.查询每门课程被选修的学生数
select COUNT(sid) from sc GROUP BY cid
22.查询出只选修了一门课程的全部学生的学号和姓名
SELECT sc.sid,MAX(sName)
FROM sc
LEFT JOIN student on student.sid = sc.sid
GROUP BY sc.sid
HAVING COUNT(cid) = 1
23.查询男生、女生人数
select SUM(CASE WHEN sSex = '男' THEN 1 ELSE 0 END) '男',
SUM(CASE WHEN sSex = '女' THEN 1 ELSE 0 END) '女'
FROM student
24.查询姓“张”的学生名单
SELECT sName FROM student WHERE sName LIKE '张%'
25.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 sName,sSex HAVING COUNT(1) > 1
26.1981年出生的学生名单(注：Student表中Sage列的类型是datetime)
SELECT SNAME, SAGE
FROM student
WHERE DATE_FORMAT(sAge,'%Y')='1981';
27.查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列
SELECT cid,AVG(score) avg_s FROM sc GROUP BY cid ORDER BY avg_s ASC ,cid DESC
28.查询平均成绩大于85的所有学生的学号、姓名和平均成绩
SELECT student.sid,MAX(sName),AVG(score) avg_s
FROM student
LEFT JOIN sc ON student.sid = sc.sid
GROUP BY student.sid
HAVING avg_s > 85
29.查询课程名称为“数据库”，且分数低于60的学生姓名和分数
SELECT sName, score
FROM sc
LEFT JOIN course on course.cid = sc.cid
LEFT JOIN student on student.sid = sc.sid
WHERE course.cName = '数据库' AND sc.score < 60
30.查询所有学生的选课情况;
SELECT student.sid,sName,cName
FROM sc
LEFT JOIN course on sc.cid = course.cid
LEFT JOIN student on student.sid = sc.sid
31.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 sName,cName,score
FROM student
LEFT JOIN sc on sc.sid = student.sid
LEFT JOIN course on course.cid = sc.cid
WHERE sc.score > 70
32.查询不及格的课程，并按课程号从大到小排列
SELECT cid,score FROM sc WHERE score < 60 ORDER BY cid DESC
33.查询课程编号为003且课程成绩在80分以上的学生的学号和姓名;
SELECT sc.sid,sName
FROM student
LEFT JOIN sc on sc.sid = student.sid
LEFT JOIN course on course.cid = sc.cid
WHERE score > 80
AND sc.cid = '003'
34.求选了课程的学生人数
34.1统计sc表的总数
SELECT COUNT(1) FROM sc;
34.2在sid上去重
SELECT COUNT(DISTINCT sid) FROM sc
35.查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩
SELECT sName,score
FROM student
LEFT JOIN sc on sc.sid = student.sid
LEFT JOIN course on course.cid = sc.cid
LEFT JOIN teacher on teacher.tid = course.tid
WHERE teacher.tName = '叶平'
ORDER BY score DESC
LIMIT 1
36.查询各个课程及相应的选修人数
SELECT cid,count(sid)
FROM sc
GROUP BY cid
37.查询不同课程成绩相同的学生的学号、课程号、学生成绩
SELECT DISTINCT a.sid,b.score
FROM sc a
LEFT JOIN sc b ON a.score = b.score
WHERE a.cid <> b.cid
38.查询每门功课成绩最好的前两名
38.1如果第二名和之后学生的成绩相同，则舍去
SELECT *
FROM sc t1
WHERE (
SELECT COUNT(*)
FROM sc t2
WHERE t1.cid=t2.cid
AND t2.score>=t1.score
) <=2 ORDER BY t1.cid,t1.score DESC
38.2如果第二名和之后学生的成绩相同，则都显示
SELECT *
FROM sc t1
WHERE (
SELECT COUNT(*)
FROM sc t2
WHERE t1.cid=t2.cid
AND t2.score>t1.score
) <=1 ORDER BY t1.cid,t1.score DESC
39.统计每门课程的学生选修人数。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 cid,COUNT(1) c
FROM sc
GROUP BY cid
ORDER BY c DESC,cid
40.检索至少选修两门课程的学生学号
SELECT sid
FROM sc
GROUP BY sid
HAVING COUNT(1) > 1
41.查询全部学生都选修的课程的课程号和课程名
SELECT sc.cid,course.cName
FROM sc
LEFT JOIN course on course.cid = sc.cid
GROUP BY sc.cid
HAVING COUNT(1) = (SELECT COUNT(1) FROM student)
42.****查询没学过“叶平”老师讲授的任一门课程的学生姓名 ****
SELECT sName
FROM student
WHERE sid NOT IN (
SELECT sid
FROM teacher
LEFT JOIN course on course.tid = teacher.tid
LEFT JOIN sc on sc.cid = course.cid
WHERE tName = '叶平')
43.查询两门以上不及格课程的同学的学号及其平均成绩
SELECT student.sid,AVG(score)
FROM sc
LEFT JOIN student on student.sid = sc.sid
GROUP BY sc.sid
HAVING SUM(CASE WHEN score<60 THEN 1 ELSE 0 END) > 1
44.检索“004”课程分数小于60，按分数降序排列的同学学号
SELECT sid
FROM sc
WHERE cid = '004'
ORDER BY sid
45.删除“1002”同学的“001”课程的成绩
delete from Sc where sid='1002' and cid='001';
金融理财师（AFP）双证
注册理财规划师（CFP）四证
出证单位：中国注册理财规划师协会。
适合人群如下：
1.银行工作人员
2.证劵公司工作人员
3.理财投资公司工作人员
4.社会投资理财顾问人员。
查询网址：中国注册理财规划师协会http://www.cfp.org.cn。
