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SQL 经典练习题

数据准备

1.学生表
2.课程表
3.教师表
4.成绩表

-- 建表
-- 学生表
CREATE TABLE `Student`(
`s_id` VARCHAR(20),
`s_name` VARCHAR(20) NOT NULL DEFAULT '',
`s_birth` VARCHAR(20) NOT NULL DEFAULT '',
`s_sex` VARCHAR(10) NOT NULL DEFAULT '',
PRIMARY KEY(`s_id`)
);
-- 课程表
CREATE TABLE `Course`(
`c_id` VARCHAR(20),
`c_name` VARCHAR(20) NOT NULL DEFAULT '',
`t_id` VARCHAR(20) NOT NULL,
PRIMARY KEY(`c_id`)
);
-- 教师表
CREATE TABLE `Teacher`(
`t_id` VARCHAR(20),
`t_name` VARCHAR(20) NOT NULL DEFAULT '',
PRIMARY KEY(`t_id`)
);
-- 成绩表
CREATE TABLE `Score`(
`s_id` VARCHAR(20),
`c_id` VARCHAR(20),
`s_score` INT(3),
PRIMARY KEY(`s_id`,`c_id`)
);
-- 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');
-- 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');

-- 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');

-- 成绩表测试数据
insert into Score values('01' , '01' , 80);
insert into Score values('01' , '02' , 90);
insert into Score values('01' , '03' , 99);
insert into Score values('02' , '01' , 70);
insert into Score values('02' , '02' , 60);
insert into Score values('02' , '03' , 80);
insert into Score values('03' , '01' , 80);
insert into Score values('03' , '02' , 80);
insert into Score values('03' , '03' , 80);
insert into Score values('04' , '01' , 50);
insert into Score values('04' , '02' , 30);
insert into Score values('04' , '03' , 20);
insert into Score values('05' , '01' , 76);
insert into Score values('05' , '02' , 87);
insert into Score values('06' , '01' , 31);
insert into Score values('06' , '03' , 34);
insert into Score values('07' , '02' , 89);
insert into Score values('07' , '03' , 98);

题目

  1. 查询”01”课程比”02”课程成绩高的学生的信息及课程分数(如果没有成绩,则不算)
select 
st.*,
sc1.s_score as '01',
sc2.s_score as '02'
from Student st
left join Score sc1
on st.s_id=sc1.s_id and sc1.c_id='01'
left join Score sc2
on st.s_id=sc2.s_id and sc2.c_id='02'
where sc1.s_score > sc2.s_score
  1. 查询”01”课程比”02”课程成绩低的学生的信息及课程分数(如果没有成绩,则不算)
select 
st.*,
sc1.s_score as '01',
sc2.s_score as '02'
from Student st
left join Score sc1
on st.s_id=sc1.s_id and sc1.c_id='01'
left join Score sc2
on st.s_id=sc2.s_id and sc2.c_id='02'
where sc1.s_score < sc2.s_score
  1. 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 
st.s_id,
st.s_name,
round(avg(sc.s_score))
from Student st
left join Score sc
on st.s_id=sc.s_id
group by st.s_id
having avg(sc.s_score) > 60
  1. 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(包括有成绩的和无成绩的)
select 
st.s_id,
st.s_name,
round(avg(sc.s_score))
from Student st
left join Score sc
on st.s_id=sc.s_id
group by st.s_id
having avg(sc.s_score) < 60 or avg(sc.s_score) is null
  1. 查询所有同学的学生编号、学生姓名、考试总数、所有课程的总成绩(总成绩为空,显示 0)
select 
st.s_id,
st.s_name,
count(sc.c_id) as sc_count,
sum(
case when sc.s_score is not null
then sc.s_score
else 0
end) as sc_total_score
from Student st
left join Score sc
on st.s_id=sc.s_id
group by st.s_id
  1. 查询”李”姓老师的数量
select count(t_id) as count from Teacher where t_name like '李%'
  1. 查询学过”张三”老师授课的同学的信息
select st.* from Student st
left join Score sc
on st.s_id=sc.s_id
left join Course c
on sc.c_id=c.c_id
left join Teacher t
on c.t_id=t.t_id
where t.t_name='张三'
  1. 查询没学过”张三”老师授课的同学的信息
select * from Student 
where s_id not in (
select st.s_id from Student st
left join Score sc
on st.s_id=sc.s_id
left join Course c
on sc.c_id=c.c_id
left join Teacher t
on c.t_id=t.t_id
where t.t_name='张三'
)
  1. 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 st.* from Student st
left join Score sc
on st.s_id=sc.s_id and sc.c_id='01'
left join Score sc2
on st.s_id=sc2.s_id and sc2.c_id='02'
where sc.c_id is not null and sc2.c_id is not null
  1. 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 st.* from Student st
left join Score sc
on st.s_id=sc.s_id and sc.c_id='01'
left join Score sc2
on st.s_id=sc2.s_id and sc2.c_id='02'
where sc.c_id is not null and sc2.c_id is null
  1. 查询没有学全所有课程的同学的信息
select st.* from Student st
left join Score sc
on st.s_id=sc.s_id and sc.c_id='01'
left join Score sc2
on st.s_id=sc2.s_id and sc2.c_id='02'
left join Score sc3
on st.s_id=sc3.s_id and sc3.c_id='03'
where sc.c_id is null or sc2.c_id is null or sc3.c_id is null
  1. 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 st2.* from Student st2
left join Score sc2
on st2.s_id=sc2.s_id
where sc2.c_id in (
select sc.c_id from Student st
left join Score sc
on st.s_id=sc.s_id
where st.s_id='01'
) and st2.s_id != '01'
  1. 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 st2.s_id  from Student st2
left join Score sc2
on st2.s_id=sc2.s_id
where st2.s_id != '01'
group by st2.s_id
having GROUP_CONCAT(sc2.c_id) =
(
select GROUP_CONCAT(sc.c_id) from Student st
left join Score sc
on st.s_id=sc.s_id
where st.s_id='01'
GROUP BY st.s_id
)
  1. 查询没学过”张三”老师讲授的任一门课程的学生姓名
select st2.s_name from  Student st2
where st2.s_name not in (
select st.s_name from Student st
left join Score sc
on st.s_id=sc.s_id
left join Course c
on sc.c_id=c.c_id
left join Teacher t
on c.t_id=t.t_id
WHERE t.t_name='张三'
GROUP BY st.s_name
)
  1. 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 st.s_id, st.s_name, avg(sc.s_score) from Student st
left join Score sc
on st.s_id=sc.s_id
where sc.s_score < 60
group by st.s_id, st.s_name
having count(sc.s_score) >= 2
  1. 检索”01”课程分数小于 60,按分数降序排列的学生信息
select st.* from Student st
left join Score sc
on sc.s_id=st.s_id
where sc.s_score < 60 and sc.c_id='01'
order by sc.s_score desc
  1. 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 st.s_name, 
sum(case when sc.c_id='01' then sc.s_score else 0 end) as c_01,
sum(case when sc.c_id='02' then sc.s_score else 0 end) as c_02,
sum(case when sc.c_id='03' then sc.s_score else 0 end) as c_03,
avg(sc.s_score) as avg
from Score sc
left join Student st
on st.s_id=sc.s_id
group by st.s_name
  1. 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 
c.c_id,
c.c_name,
max(sc.s_score),
min(sc.s_score),
avg(sc.s_score),
(select count(1) from Score where c_id=c.c_id and s_score >= 60) * 100/
(select count(1) from Score where c_id=c.c_id),
(select count(1) from Score where c_id=c.c_id and s_score >= 70 and s_score < 80) * 100/
(select count(1) from Score where c_id=c.c_id),
(select count(1) from Score where c_id=c.c_id and s_score >= 80 and s_score < 90) * 100/
(select count(1) from Score where c_id=c.c_id),
(select count(1) from Score where c_id=c.c_id and s_score >= 90) * 100/
(select count(1) from Score where c_id=c.c_id)
from Course c
left join Score sc
on sc.c_id=c.c_id
group by c.c_id, c.c_name;
  1. 查询学生的总成绩并进行排名
select 
st.s_name,
case when sum(sc.s_score) is null then 0 else sum(sc.s_score) end as sum
from Student st
left join Score sc
on sc.s_id=st.s_id
group by st.s_name
order by sum(sc.s_score) desc
  1. 查询不同老师所教不同课程平均分从高到低显示
select t.t_name, c.c_name, avg(sc.s_score) 
from Teacher t
left join Course c
on c.t_id=t.t_id
left join Score sc
on sc.c_id=c.c_id
group by t.t_name, c.c_name
order by avg(sc.s_score) desc
  1. 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 
c.c_id,
c.c_name,
(select count(1) from Score sc where sc.c_id=c.c_id and sc.s_score <= 100 and sc.s_score > 85) as '100-85',
(select count(1) from Score sc where sc.c_id=c.c_id and sc.s_score <= 85 and sc.s_score > 70) as '85-70',
(select count(1) from Score sc where sc.c_id=c.c_id and sc.s_score <= 70 and sc.s_score > 60) as '70-60',
(select count(1) from Score sc where sc.c_id=c.c_id and sc.s_score <= 60 and sc.s_score >= 0) as '0-60'
from Course c
  1. 查询每门课程被选修的学生数
select 
c.c_id,
count(1)
from Course c
left join Score sc
on sc.c_id=c.c_id
left join Student st
on st.s_id=sc.s_id
group by c.c_id
  1. 查询出只有两门课程的全部学生的学号和姓名
select st.s_id, st.s_name from Student st
left join Score sc
on sc.s_id=st.s_id
group by st.s_id, st.s_name
having count(sc.c_id) = 2
  1. 查询男生、女生人数
select s_sex, count(1) from Student group by s_sex 
  1. 查询名字中含有”风”字的学生信息
select * from Student where s_name like '%风%'
  1. 查询同名同性学生名单,并统计同名人数
select 
st.s_name,
count(1)
from Student st
group by st.s_name
having count(st.s_name) > 1
  1. 查询 1990 年出生的学生名单
select * from Student where s_birth like '1990%'
  1. 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
select c.c_id, c.c_name, avg(sc.s_score) from Course c
left join Score sc
on sc.c_id=c.c_id
group by c.c_id, c.c_name
order by avg(sc.s_score) desc, c.c_id asc
  1. 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 st.s_id, st.s_name, avg(sc.s_score) from Student st
left join Score sc
on sc.s_id=st.s_id
group by st.s_id, st.s_name
having avg(sc.s_score) >= 85
  1. 查询课程名称为”数学”,且分数低于 60 的学生姓名和分数
select st.s_name, sc.s_score from Student st
left join Score sc
on sc.s_id=st.s_id
left join Course c
on c.c_id=sc.c_id
where c.c_name='数学'
and sc.s_score < 60