复杂sql语句练习（mysql）

下面是练习表数据和结构

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for course
-- ----------------------------
DROP TABLE IF EXISTS `course`;
CREATE TABLE `course` (
  `id` int(11) NOT NULL,
  `name` varchar(22) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of course
-- ----------------------------
INSERT INTO `course` VALUES ('30001', '物理');
INSERT INTO `course` VALUES ('30002', '政治');
INSERT INTO `course` VALUES ('30003', '语文');
INSERT INTO `course` VALUES ('30004', '高数');
INSERT INTO `course` VALUES ('30005', '英语');

-- ----------------------------
-- Table structure for student
-- ----------------------------
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student` (
  `id` int(11) NOT NULL,
  `name` varchar(22) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of student
-- ----------------------------
INSERT INTO `student` VALUES ('10001', 'tom');
INSERT INTO `student` VALUES ('10002', 'json');
INSERT INTO `student` VALUES ('10003', 'ak');
INSERT INTO `student` VALUES ('10004', 'km');
INSERT INTO `student` VALUES ('10005', 'mk');

-- ----------------------------
-- Table structure for student_course
-- ----------------------------
DROP TABLE IF EXISTS `student_course`;
CREATE TABLE `student_course` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `student_id` int(11) NOT NULL,
  `course_id` int(11) NOT NULL,
  `teacher_id` int(11) NOT NULL,
  `score` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=51 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of student_course
-- ----------------------------
INSERT INTO `student_course` VALUES ('4', '10001', '30002', '20002', '82');
INSERT INTO `student_course` VALUES ('6', '10001', '30003', '20003', '82');
INSERT INTO `student_course` VALUES ('8', '10001', '30004', '20005', '82');
INSERT INTO `student_course` VALUES ('10', '10001', '30005', '20005', '82');
INSERT INTO `student_course` VALUES ('12', '10002', '30001', '20001', '90');
INSERT INTO `student_course` VALUES ('14', '10002', '30002', '20002', '92');
INSERT INTO `student_course` VALUES ('16', '10002', '30003', '20003', '62');
INSERT INTO `student_course` VALUES ('18', '10002', '30004', '20004', '82');
INSERT INTO `student_course` VALUES ('20', '10002', '30005', '20005', '82');
INSERT INTO `student_course` VALUES ('22', '10003', '30001', '20001', '69');
INSERT INTO `student_course` VALUES ('24', '10003', '30002', '20002', '89');
INSERT INTO `student_course` VALUES ('26', '10003', '30003', '20003', '99');
INSERT INTO `student_course` VALUES ('28', '10003', '30004', '20004', '82');
INSERT INTO `student_course` VALUES ('30', '10003', '30005', '20005', '82');
INSERT INTO `student_course` VALUES ('32', '10004', '30001', '20001', '92');
INSERT INTO `student_course` VALUES ('34', '10004', '30002', '20002', '93');
INSERT INTO `student_course` VALUES ('36', '10004', '30003', '20003', '73');
INSERT INTO `student_course` VALUES ('38', '10004', '30004', '20004', '82');
INSERT INTO `student_course` VALUES ('40', '10004', '30005', '20005', '82');
INSERT INTO `student_course` VALUES ('42', '10005', '30001', '20001', '95');
INSERT INTO `student_course` VALUES ('44', '10005', '30002', '20002', '75');
INSERT INTO `student_course` VALUES ('46', '10005', '30003', '20003', '79');
INSERT INTO `student_course` VALUES ('48', '10005', '30004', '20004', '82');
INSERT INTO `student_course` VALUES ('50', '10005', '30005', '20005', '82');

-- ----------------------------
-- Table structure for teacher
-- ----------------------------
DROP TABLE IF EXISTS `teacher`;
CREATE TABLE `teacher` (
  `id` int(11) NOT NULL,
  `name` varchar(22) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of teacher
-- ----------------------------
INSERT INTO `teacher` VALUES ('20001', 'su');
INSERT INTO `teacher` VALUES ('20002', 'wang');
INSERT INTO `teacher` VALUES ('20003', 'zhou');
INSERT INTO `teacher` VALUES ('20004', 'yang');
INSERT INTO `teacher` VALUES ('20005', 'liu');

 

4个表，包括student，course，student_course,teacher 

详细练习：

-- 1.查询物理成绩比英语成绩高的所有学生
select * from 
(select * from student_course WHERE course_id=30001) a,
(select * from student_course WHERE course_id=30005) b 
where a.score>b.score and a.student_id=b.student_id;

-- 2.查询平均成绩大于60分的同学的学号和平均成绩； 
select  a.student_id,avg(a.score) from
student_course a
 GROUP BY a.student_id
having avg(a.score)>60 ;

-- 3查询所有同学的学号,姓名、选课数、总成绩；
select b.student_id,a.name,COUNT(b.course_id),SUM(b.score)
from student a ,student_course b
where a.id=b.student_id
GROUP BY b.student_id ;

-- 4、查询名字l开头的老师的个数；
select COUNT(DISTINCT(name)) FROM teacher where name like 'l%';

-- -- 5,查询没学过“liu”老师课的同学的学号、姓名；
select * from student where  id not in(
select DISTINCT(student_id) from student_course where teacher_id=(
select DISTINCT(id) from teacher where name="liu")
);

-- 6 学过30001和30002课程的同学的学号、姓名；-- 
select a.student_id,b.name
 from student_course a,student b
 where  a.student_id=b.id and a.course_id=30001  and exists(
 select* from student_course  s2 where s2.student_id=a.student_id and s2.course_id=30002
 )
 group by a.student_id;
 
  -- 7  学过30001和30002课程的同学的学号
 select a.student_id from
 (select * from student_course where course_id=30001) a  inner  join 
 (select * from student_course where course_id=30002) b 
 on a.student_id=b.student_id;
 
 -- 8 、查询学过“liu”老师所教的所有课的同学的学号、姓名；
select * from student where  id in
(
select distinct(student_id) from student_course where teacher_id= 
(
select distinct(id) from teacher where name="liu"
)
);

-- 9查询课程编号“30002”的成绩比课程编号“30001”课程低的所有同学的学号、姓名；
select*from student where id in(
select  distinct(a.student_id) from
(select * from student_course where course_id=30002) a inner join (select * from student_course where course_id=30001) b 
on a.score ;

-- 10 查询没有学全所有课的同学的学号、姓名
select a.student_id,b.name
from student_course a,student b
where a.student_id=b.id 
group by a.student_id
having count(a.course_id) <> (select count(*) from course);

-- 11查询所有课程成绩小于90分的同学的学号、姓名；
select * from student where id not in (
select student_id from student_course  where score>90
);

-- 12查询至少学过学号为“10001”同学所有一门课的其他同学学号和姓名
select *from student where id in (
    SELECT distinct(student_id) FROM student_course where student_id <> 10001 and course_id in 
    (
   SELECT course_id FROM student_course where student_id=10001
   )
   );
   
   select distinct a.id,a.name from student a, student_course b where a.id=b.student_id and b.student_id <> 10001 and b.course_id in(
    SELECT course_id FROM student_course where student_id=10001
   );
   
-- 13把“student_course”表中“liu”老师教的课的成绩都更改为此课程的平均成绩
update student_course set score =(
select score1 from (
select avg(b.score) as score1 from teacher a,student_course b where a.name="liu" and b.teacher_id=a.id
) 
as tablename2
)where teacher_id=(select id from teacher where name="liu");

select * from student_course;
update student_course set score=82.1667 where  teacher_id=20004;
SET SQL_SAFE_UPDATES = 0;
show variables like 'SQL_SAFE_UPDATES';

-- 14查询和“10002”号的同学学习的课程完全相同的其他同学学号和姓名；

 select b.id,b.name from student_course a,student b
 where a.course_id in(
  select course_id from student_course where student_id=10002
 ) and a.student_id=b.id and a.student_id <> 10002
 group by b.id
 having count(*)=(select count(*) from student_course where student_id=10002);
 
 
--  15 删除学习“su”老师课的student_course表记录；
delete  from student_course 
where teacher_id=(
select id from teacher where name="su"
);

-- 16查找要求符合以下条件：没有上过编号“30003”课程的同学学号、
-- "30003"号课的平均成绩；
select id,(select avg(score) from student_course where course_id="30003") from student where id not in(
select student_id from student_course where course_id="30003"
);

-- 17按平均成绩从高到低显示所有学生的“物理”、“政治”、“英语”三门的课程成绩，
-- 按如下形式显示： 学生ID,物理,政治,英语,有效课程数,有效平均分 
select  t.student_id as 学生ID,
(select score from student_course where t.student_id=student_id and   course_id="30001" ) as 物理,
(select score from student_course where t.student_id=student_id and   course_id="30002" ) as 政治,
(select score from student_course where  t.student_id=student_id and  course_id="30005" ) as 英语,
count(*)  AS 有效课程数, AVG(t.score) AS 平均成绩
from student_course t
group by t.student_id
order by avg(t.score);

-- 18 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 course_id as 课程ID,max(score) as 最高分,min(score) as 最低分
from student_course 
group by course_id;

-- 19 按各科平均成绩从低到高和及格率
select course_id as 课程ID,avg(score) as 平均成绩,
100*sum(case when score>=60 then 1 else 0 end) /count(*) as  及格百分数
from student_course  t
group by course_id
order by avg(score)  desc;

-- 20.查询如下课程平均成绩和及格率的百分数(用"1行"显示):
--  物理（30001），政治（30002），语文 （30003），高数（30004） 

select 
(select  avg(score) from student_course where course_id="30001") as 物理,
(select  avg(score) from student_course where course_id="30002") as 政治,
(select  avg(score) from student_course where course_id="30003") as 语文,
(select  avg(score) from student_course where course_id="30004") as 高数,
100*sum(case when score>=60 then 1 else 0 end)/count(*) as 及格率,
avg (score) as 平均成绩
from student_course
group by course_id;

-- 21 查询不同老师所教不同课程平均分从高到低显示 
select avg(score)
from student_course
group by teacher_id
order by avg(score) desc;

-- 22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] 
select a.course_id as 课程ID,
b.name as 课程名称,
sum(case when a.score between 85 and 100 then 1 else 0 end) as "[100-85]",
sum(case when a.score between 70 and 85 then 1 else 0 end) as "[85-70]",
sum(case when a.score between 65 and 70 then 1 else 0 end) as "[70-60]",
sum(case when a.score <60 then 1 else 0 end) as "[<60]"
from student_course a,course b
where a.course_id=b.id
group by a.course_id,b.name;

-- 23 查询学生平均成绩
select a.student_id as 学生ID,b.name as 姓名,avg(a.score)  as 平均成绩
from student_course a,student b
where a.student_id=b.id
group by a.student_id
order by avg(a.score) desc;

-- 24 查询各科成绩前三名的记录:(不考虑成绩并列情况)
SELECT t1.student_id as 学生ID,
       t1.course_id as 课程ID,
       t1.score as 分数 
      FROM student_course t1 
      WHERE t1.id IN (
      select t.id from(
      SELECT id 
              FROM student_course 
            ORDER BY score DESC 
            limit 3) as t 
              ) 
      ORDER BY t1.score desc;
   
-- 25查询每门课程被选修的学生数
select count(student_id)
from student_course
group by course_id;

-- 26 查询出只选修了一门课程的全部学生的学号和姓名 
select a.student_id,b.name
from student_course a,student b
where b.id=a.student_id
group by student_id
having count(course_id)=1;

-- 27 查询姓“t”的学生名单
select * from student where name like "t%" ;

-- 28 查询同名同性学生名单，并统计同名人数 
select name ,count(name) from student group by name;

-- 29 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 avg(score) ,course_id from student_course group by course_id order by avg(score),course_id desc ;

-- 30 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 a.student_id,b.name,avg(a.score)
from student_course a,student b
where a.student_id=b.id
group by  a.student_id
having avg(a.score)>85;

-- 31 查询课程名称为“政治”，且分数低于60的学生姓名和分数 
select  a.student_id,a.score,b.name
from student_course a,student b
where a.student_id=b.id and a.course_id=(
select id from course where name ="政治"
)
group by  a.student_id,a.score
having a.score <60;

-- 32查询所有学生的选课情况； 
select  a.student_id,a.course_id,b.name,c.name
from student_course a,student b,course c
where a.student_id=b.id and a.course_id=c.id
group by  a.student_id,a.course_id;

-- 33 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  a.student_id,a.course_id,a.score,b.name,c.name
from student_course a,student b,course c
where a.student_id=b.id and a.course_id=c.id 
group by  a.student_id,a.course_id,a.score
having a.score>70;

-- 34 查询不及格的课程，并按课程号从大到小排列
select course_id,score
from student_course
group by course_id,score
having score<60
order by course_id;

-- 35 查询课程编号为30003且课程成绩在80分以上的学生的学号和姓名；
select a.student_id,a.score,a.course_id,b.name
from student_course a ,student b
where a.student_id=b.id and a.course_id="30003"
group by a.student_id,a.score,a.course_id
having a.score>80;

-- 36求选了课程的学生人数 
select count(distinct student_id) from student_course;

-- 37 查询选修“liu”老师所授课程的学生中，成绩最高的学生姓名及其成绩 
select b.name,a.score
from student_course a,student b,course c,teacher d
where a.course_id=c.id and a.student_id=b.id and a.teacher_id=d.id and d.name="liu"
and a.score=(select max(score) from student_course where course_id=c.id);

-- 38查询各个课程及相应的选修人数 
select course_id,count(student_id)
from student_course
group by course_id;

-- 39 查询不同课程成绩相同的学生的学号、课程号、学生成绩 
select a.student_id,a.course_id,a.score
from student_course a,student_course b
where a.score=b.score and a.course_id <> b.course_id;

-- 40 查询每门功成绩最好的前两名
select * from student_course where score in(
select score from(
select score from student_course limit 2
) as a
)
order by course_id desc;

-- 41 统计每门课程的学生选修人数（超过4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，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 course_id, count(*) 
from student_course 
group by course_id
 having count(*)>4
 order by count(*),course_id desc; 
 
 -- 42 检索至少选修两门课程的学生学号
select student_id
 from student_course
 group by student_id
 having count(*)>=2;
 
 -- 43 、查询全部学生都选修的课程的课程号和课程名
 select *
 from course
 where id in(
 select course_id from student_course group by course_id having count(*)=(select count(*) from student)
);

-- 44 查询没学过“yang”老师讲授的课程的学生姓名 
select name from student where id not in(
select distinct a.student_id
from student_course a,teacher c
where  a.teacher_id=c.id and c.name = "yang"
 );

-- 45 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_id,avg(score)
from student_course
where score <60
group by student_id
having count(*) >=2;

-- 46 检索“30004”课程分数小于60，按分数降序排列的同学学号
select student_id
from student_course
where course_id="30004" and score<60
group by student_id,score
order by score desc; 

-- 47 删除“10002”同学的“30001”课程的成绩 
delete from student_course where student_id=10002 and course_id=30002;