sql语句练习50题(Mysql版) 围观

–1.学生表 
Student(s_id,s_name,s_birth,s_sex) –学生编号,学生姓名, 出生年月,学生性别 
–2.课程表 
Course(c_id,c_name,t_id) – –课程编号, 课程名称, 教师编号 
–3.教师表 
Teacher(t_id,t_name) –教师编号,教师姓名 
–4.成绩表 
Score(s_id,c_id,s_score) –学生编号,课程编号,分数

测试数据

--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);

表数据如下:

-- 准备条件,去掉 sql_mode 的 ONLY_FULL_GROUP_BY 否则此种情况下会报错:
-- Expression #1 of select list is not in group by clause and contains nonaggregated column ‘userinfo.
-- 原因：
-- MySQL 5.7.5和up实现了对功能依赖的检测。如果启用了only_full_group_by SQL模式(在默认情况下是这样)，
-- 那么MySQL就会拒绝选择列表、条件或顺序列表引用的查询，这些查询将引用组中未命名的非聚合列，而不是在功能上依赖于它们。
-- (在5.7.5之前，MySQL没有检测到功能依赖项，only_full_group_by在默认情况下是不启用的。关于前5.7.5行为的描述，请参阅MySQL 5.6参考手册。)
-- 执行以下个命令，可以查看 sql_mode 的内容。
SHOW SESSION VARIABLES;
SHOW GLOBAL VARIABLES;
select @@sql_mode;
-- 更改
set global sql_mode=‘STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION‘;
set session sql_mode=‘STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION‘;

练习题和sql语句

-- 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 st.*,sc.s_score as ‘语文‘ ,sc2.s_score ‘数学‘ 
from student st
left join score sc on sc.s_id=st.s_id and sc.c_id=‘01‘ 
left join score sc2 on sc2.s_id=st.s_id and sc2.c_id=‘02‘  
where sc.s_score>sc2.s_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
select st.*,sc.s_score ‘语文‘,sc2.s_score ‘数学‘ from student st
left join score sc on sc.s_id=st.s_id and sc.c_id=‘01‘
left join score sc2 on sc2.s_id=st.s_id and sc2.c_id=‘02‘
where sc.s_score<sc2.s_score

-- 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 st.s_id,st.s_name,ROUND(AVG(sc.s_score),2) "平均成绩" from student st
left join score sc on sc.s_id=st.s_id
group by st.s_id having AVG(sc.s_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
        -- (包括有成绩的和无成绩的)
select st.s_id,st.s_name,(case when ROUND(AVG(sc.s_score),2) is null then 0 else ROUND(AVG(sc.s_score),2) end ) "平均成绩" from student st
left join score sc on sc.s_id=st.s_id
group by st.s_id having AVG(sc.s_score)<60 or AVG(sc.s_score) is NULL

-- 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


select st.s_id,st.s_name,count(sc.c_id) "选课总数",sum(case when sc.s_score is null then 0 else sc.s_score end) "总成绩" 
from student st 
left join score sc on st.s_id = sc.s_id 
group by st.s_id

-- 6、查询"李"姓老师的数量 
select t.t_name,count(t.t_id) from teacher t
group by t.t_id having t.t_name like "李%"; 

-- 7、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 sc.s_id=st.s_id
left join course c on c.c_id=sc.c_id
left join teacher t on t.t_id=c.t_id
 where t.t_name="张三"

-- 8、查询没学过"张三"老师授课的同学的信息 
 -- 张三老师教的课
 select c.* from course c left join teacher t on t.t_id=c.t_id where  t.t_name="张三"
 -- 有张三老师课成绩的st.s_id
 select sc.s_id from score sc where sc.c_id in (select c.c_id from course c left join teacher t on t.t_id=c.t_id where  t.t_name="张三")
 -- 不在上面查到的st.s_id的学生信息,即没学过张三老师授课的同学信息
 select st.* from student st where st.s_id not in(
  select sc.s_id from score sc where sc.c_id in (select c.c_id from course c left join teacher t on t.t_id=c.t_id where  t.t_name="张三")
  )

-- 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 st.* from student st 
inner join score sc on sc.s_id = st.s_id
inner join course c on c.c_id=sc.c_id and c.c_id="01"
where st.s_id in (
select st2.s_id from student st2 
inner join score sc2 on sc2.s_id = st2.s_id
inner join course c2 on c2.c_id=sc2.c_id and c2.c_id="02"
)



select a.* 
from
    student a,
    score b,
    score c
where
    a.s_id = b.s_id
    and a.s_id = c.s_id
    and b.c_id = ‘01‘
    and c.c_id = ‘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 st.* from student st 
inner join score sc on sc.s_id = st.s_id
inner join course c on c.c_id=sc.c_id and c.c_id="01"
where st.s_id not in (
select st2.s_id from student st2 
inner join score sc2 on sc2.s_id = st2.s_id
inner join course c2 on c2.c_id=sc2.c_id and c2.c_id="02"
)

-- 11、查询没有学全所有课程的同学的信息
select * from student where s_id not in (
select st.s_id from student st 
inner join score sc on sc.s_id = st.s_id and sc.c_id="01"
where st.s_id  in (
select st1.s_id from student st1 
inner join score sc2 on sc2.s_id = st1.s_id and sc2.c_id="02"
) and st.s_id in (
select st2.s_id from student st2 
inner join score sc2 on sc2.s_id = st2.s_id and sc2.c_id="03"
))



select a.*
from student a
left join score b on a.s_id = b.s_id
group by
a.s_id
having
count(b.c_id) != ‘3‘;


-- 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 distinct st.* from student st 
left join score sc on sc.s_id=st.s_id
where sc.c_id in (
select sc2.c_id from student st2
left join score sc2 on sc2.s_id=st2.s_id
where st2.s_id =‘01‘
)

-- 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  st.* from student st 
left join score sc on sc.s_id=st.s_id
group by st.s_id
having group_concat(sc.c_id) = 
(
select  group_concat(sc2.c_id) from student st2
left join score sc2 on sc2.s_id=st2.s_id
where st2.s_id =‘01‘
)

-- 14、查询没学过"张三"老师讲授的任一门课程的学生姓名
select st.s_name from student st 
where st.s_id not in (
select sc.s_id from score sc 
inner join course c on c.c_id=sc.c_id
inner join teacher t on t.t_id=c.t_id and t.t_name="张三"
)

-- 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 st.s_id,st.s_name,avg(sc.s_score) from student st
left join score sc on sc.s_id=st.s_id
where sc.s_id in (
select sc.s_id from score sc 
where sc.s_score<60 or sc.s_score is NULL
group by sc.s_id having COUNT(1)>=2
)
group by st.s_id

-- 16、检索"01"课程分数小于60，按分数降序排列的学生信息
select st.*,sc.s_score from student st 
inner join score sc on sc.s_id=st.s_id and sc.c_id="01" and sc.s_score<60
order by sc.s_score desc



select st.*,sc.s_score from student st 
left join score sc on sc.s_id=st.s_id 
where sc.c_id="01" and sc.s_score<60
order by sc.s_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 st.s_id,st.s_name,avg(sc4.s_score) "平均分",sc.s_score "语文",sc2.s_score "数学",sc3.s_score "英语" from student st
left join score sc  on sc.s_id=st.s_id  and sc.c_id="01"
left join score sc2 on sc2.s_id=st.s_id and sc2.c_id="02"
left join score sc3 on sc3.s_id=st.s_id and sc3.c_id="03"
left join score sc4 on sc4.s_id=st.s_id
group by st.s_id 
order by avg(sc4.s_score) desc


select st.s_id,st.s_name,
(case when avg(sc4.s_score) is null then 0 else avg(sc4.s_score) end) "平均分",
(case when sc.s_score is null then 0 else sc.s_score end) "语文",
(case when sc2.s_score is null then 0 else sc2.s_score end) "数学",
(case when sc3.s_score is null then 0 else sc3.s_score end) "英语" 
from student st
left join score sc  on sc.s_id=st.s_id  and sc.c_id="01"
left join score sc2 on sc2.s_id=st.s_id and sc2.c_id="02"
left join score sc3 on sc3.s_id=st.s_id and sc3.c_id="03"
left join score sc4 on sc4.s_id=st.s_id
group by st.s_id 
order by avg(sc4.s_score) 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 c.c_id,c.c_name,max(sc.s_score) "最高分",MIN(sc2.s_score) "最低分",avg(sc3.s_score) "平均分" 
,((select count(s_id) from score where s_score>=60 and c_id=c.c_id )/(select count(s_id) from score where c_id=c.c_id)) "及格率"
,((select count(s_id) from score where s_score>=70 and s_score<80 and c_id=c.c_id )/(select count(s_id) from score where c_id=c.c_id)) "中等率"
,((select count(s_id) from score where s_score>=80 and s_score<90 and c_id=c.c_id )/(select count(s_id) from score where c_id=c.c_id)) "优良率"
,((select count(s_id) from score where s_score>=90 and c_id=c.c_id )/(select count(s_id) from score where c_id=c.c_id)) "优秀率"
from course c
left join score sc on sc.c_id=c.c_id 
left join score sc2 on sc2.c_id=c.c_id 
left join score sc3 on sc3.c_id=c.c_id 
group by c.c_id

-- 19、按各科成绩进行排序，并显示排名(实现不完全)
-- mysql没有rank函数
-- 加@score是为了防止用union all 后打乱了顺序
select c1.s_id,c1.c_id,c1.c_name,@score:=c1.s_score,@i:=@i+1 from (select c.c_name,sc.* from course c 
left join score sc on sc.c_id=c.c_id
where c.c_id="01" order by sc.s_score desc) c1 ,
(select @i:=0) a
union all 
select c2.s_id,c2.c_id,c2.c_name,c2.s_score,@ii:=@ii+1 from (select c.c_name,sc.* from course c 
left join score sc on sc.c_id=c.c_id

                        

                            

                                
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