mysql基础（二）之练习题

表数据与表结构：

/*
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 Source Server         : localhost
 Source Server Type    : MySQL
 Source Server Version : 50624
 Source Host           : localhost
 Source Database       : sqlexam

 Target Server Type    : MySQL
 Target Server Version : 50624
 File Encoding         : utf-8

 Date: 10/21/2016 06:46:46 AM
*/

SET NAMES utf8;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
--  Table structure for `class`
-- ----------------------------
DROP TABLE IF EXISTS `class`;
CREATE TABLE `class` (
  `cid` int(11) NOT NULL AUTO_INCREMENT,
  `caption` varchar(32) NOT NULL,
  PRIMARY KEY (`cid`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;

-- ----------------------------
--  Records of `class`
-- ----------------------------
BEGIN;
INSERT INTO `class` VALUES ('1', '三年二班'), ('2', '三年三班'), ('3', '一年二班'), ('4', '二年九班');
COMMIT;

-- ----------------------------
--  Table structure for `course`
-- ----------------------------
DROP TABLE IF EXISTS `course`;
CREATE TABLE `course` (
  `cid` int(11) NOT NULL AUTO_INCREMENT,
  `cname` varchar(32) NOT NULL,
  `teacher_id` int(11) NOT NULL,
  PRIMARY KEY (`cid`),
  KEY `fk_course_teacher` (`teacher_id`),
  CONSTRAINT `fk_course_teacher` FOREIGN KEY (`teacher_id`) REFERENCES `teacher` (`tid`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;

-- ----------------------------
--  Records of `course`
-- ----------------------------
BEGIN;
INSERT INTO `course` VALUES ('1', '生物', '1'), ('2', '物理', '2'), ('3', '体育', '3'), ('4', '美术', '2');
COMMIT;

-- ----------------------------
--  Table structure for `score`
-- ----------------------------
DROP TABLE IF EXISTS `score`;
CREATE TABLE `score` (
  `sid` int(11) NOT NULL AUTO_INCREMENT,
  `student_id` int(11) NOT NULL,
  `course_id` int(11) NOT NULL,
  `num` int(11) NOT NULL,
  PRIMARY KEY (`sid`),
  KEY `fk_score_student` (`student_id`),
  KEY `fk_score_course` (`course_id`),
  CONSTRAINT `fk_score_course` FOREIGN KEY (`course_id`) REFERENCES `course` (`cid`),
  CONSTRAINT `fk_score_student` FOREIGN KEY (`student_id`) REFERENCES `student` (`sid`)
) ENGINE=InnoDB AUTO_INCREMENT=53 DEFAULT CHARSET=utf8;

-- ----------------------------
--  Records of `score`
-- ----------------------------
BEGIN;
INSERT INTO `score` VALUES ('1', '1', '1', '10'), ('2', '1', '2', '9'), ('5', '1', '4', '66'), ('6', '2', '1', '8'), ('8', '2', '3', '68'), ('9', '2', '4', '99'), ('10', '3', '1', '77'), ('11', '3', '2', '66'), ('12', '3', '3', '87'), ('13', '3', '4', '99'), ('14', '4', '1', '79'), ('15', '4', '2', '11'), ('16', '4', '3', '67'), ('17', '4', '4', '100'), ('18', '5', '1', '79'), ('19', '5', '2', '11'), ('20', '5', '3', '67'), ('21', '5', '4', '100'), ('22', '6', '1', '9'), ('23', '6', '2', '100'), ('24', '6', '3', '67'), ('25', '6', '4', '100'), ('26', '7', '1', '9'), ('27', '7', '2', '100'), ('28', '7', '3', '67'), ('29', '7', '4', '88'), ('30', '8', '1', '9'), ('31', '8', '2', '100'), ('32', '8', '3', '67'), ('33', '8', '4', '88'), ('34', '9', '1', '91'), ('35', '9', '2', '88'), ('36', '9', '3', '67'), ('37', '9', '4', '22'), ('38', '10', '1', '90'), ('39', '10', '2', '77'), ('40', '10', '3', '43'), ('41', '10', '4', '87'), ('42', '11', '1', '90'), ('43', '11', '2', '77'), ('44', '11', '3', '43'), ('45', '11', '4', '87'), ('46', '12', '1', '90'), ('47', '12', '2', '77'), ('48', '12', '3', '43'), ('49', '12', '4', '87'), ('52', '13', '3', '87');
COMMIT;

-- ----------------------------
--  Table structure for `student`
-- ----------------------------
DROP TABLE IF EXISTS `student`;
CREATE TABLE `student` (
  `sid` int(11) NOT NULL AUTO_INCREMENT,
  `gender` char(1) NOT NULL,
  `class_id` int(11) NOT NULL,
  `sname` varchar(32) NOT NULL,
  PRIMARY KEY (`sid`),
  KEY `fk_class` (`class_id`),
  CONSTRAINT `fk_class` FOREIGN KEY (`class_id`) REFERENCES `class` (`cid`)
) ENGINE=InnoDB AUTO_INCREMENT=17 DEFAULT CHARSET=utf8;

-- ----------------------------
--  Records of `student`
-- ----------------------------
BEGIN;
INSERT INTO `student` VALUES ('1', '男', '1', '理解'), ('2', '女', '1', '钢蛋'), ('3', '男', '1', '张三'), ('4', '男', '1', '张一'), ('5', '女', '1', '张二'), ('6', '男', '1', '张四'), ('7', '女', '2', '铁锤'), ('8', '男', '2', '李三'), ('9', '男', '2', '李一'), ('10', '女', '2', '李二'), ('11', '男', '2', '李四'), ('12', '女', '3', '如花'), ('13', '男', '3', '刘三'), ('14', '男', '3', '刘一'), ('15', '女', '3', '刘二'), ('16', '男', '3', '刘四');
COMMIT;

-- ----------------------------
--  Table structure for `teacher`
-- ----------------------------
DROP TABLE IF EXISTS `teacher`;
CREATE TABLE `teacher` (
  `tid` int(11) NOT NULL AUTO_INCREMENT,
  `tname` varchar(32) NOT NULL,
  PRIMARY KEY (`tid`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;

-- ----------------------------
--  Records of `teacher`
-- ----------------------------
BEGIN;
INSERT INTO `teacher` VALUES ('1', '张磊老师'), ('2', '李平老师'), ('3', '刘海燕老师'), ('4', '朱云海老师'), ('5', '李杰老师');
COMMIT;

SET FOREIGN_KEY_CHECKS = 1;

2、查询“生物”课程比“物理”课程成绩高的所有学生的学号；
select A.student_id from
(select student_id,num from score left join course on score.course_id = course.cid where cname='生物') as A
inner join
(select student_id,num from score left join course on score.course_id = course.cid where cname='物理') as B
on A.student_id=B.student_id where A.num > b.num;

4、查询所有同学的学号、姓名、选课数、总成绩；
select student.sid,sname,count(course_id),sum(num) from score
left join student on score.student_id=student.sid GROUP BY student_id;
5查询姓“李”的老师的个数
select count(tid) from teacher where tname like '李%';

3查询平均成绩大于60分的同学的学号和平均成绩
select student_id,avg(num) from score group by student_id having  avg(num)>60 ;

6查询没学过“叶平”老师课的同学的学号、姓名；
select student.sid,student.sname from student
where sid not in
(select score.student_id from score where course_id in
(select cid from course left join teacher on course.teacher_id=teacher.tid
where  teacher.tname='李平老师')group by student_id);

7查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；
方法一：
select student.sid,sname from student where student.sid in
(select student.sid from student left join score on student.sid=score.student_id  where score.course_id =1)
and student.sid in
(select student.sid from student left join score on student.sid=score.student_id  where score.course_id =2);

方法二：
select score.student_id,student.sname from score
left join student on score.student_id=student.sid
where course_id = 1 or course_id = 2
group by student_id having count(course_id)> 1

9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；同2
select A.student_id from
(select student_id,num from score where course_id =1) as A
LEFT JOIN
(select student_id,num from score where course_id =2) as B
on A.student_id=B.student_id where A.num > B.num;


8查询学过“叶平”老师所教的所有课的同学的学号、姓名；
select student_id from

(select student_id,count(course_id) as li from score
where course_id in
(select cid from course left join teacher on course.teacher_id=teacher.tid
where  teacher.tname='李平老师') GROUP BY student_id) as A

where A.li> 1;


10查询有课程成绩小于60分的同学的学号、姓名；
select student.sid,sname from score left join student on score.student_id=student.sid
where number < 60;

select B.student_id,studnet.sname,avg_num from
(select student_id,avg(num) as avg_num from score GROUP BY student_id having avg(num)>60) as B
left join student on B.student_id=student.sid;

11查询没有学全所有课的同学的学号、姓名
select student_id,sname from score
LEFT JOIN student on score.student_id=student.sid
GROUP BY student_id having count(course_id)< select count(cid) from course;

12查询至少有一门课与学号为“001”的同学所学相同的同学的学号和姓名；？？？？？？？？？？？？？与 13  14  属于同一系列

select student_id,sname from score
LEFT JOIN student on score.student_id=student.sid
where course_id in
(select course_id from score where student_id=1)
and student_id !=1
GROUP BY student_id;

13查询至少学过学号为“001”同学所有课的其他同学学号和姓名
select student_id,count(1) from score where student_id != 1 and
course_id in (select course_id from score where student_id = 1)
GROUP BY student_id HAVING count(1) = (select count(course_id) from score where student_id = 1)

14查询和“002”号的同学学习的课程完全相同的其他同学学号和姓名
select student_id from score
where  student_id in (select student_id from score where student_id !=1 GROUP BY student_id HAVING count(1) = 3)
and course_id in (select course_id from score where student_id = 1)
GROUP BY student_id HAVING count(1) = 3
15删除学习“叶平”老师课的SC表记录
delete from score where course_id in
(select cid from course left join teacher on course.teacher_id=teacher.tid where teacher.tname='李平老师');


16向SC表中插入一些记录，这些记录要求符合以下条件：①没有上过编号“002”课程的同学学号；②插入“002”号课程的平均成绩；
insert into score(student_id,course_id,num) select student_id,2,(select avg(num) from score where course_id=2) from score where course_id != 2

17按平均成绩从低到高显示所有学生的“语文”、“数学”、“英语”三门的课程成绩，按如下形式显示： 学生ID,语文,数学,英语,有效课程数,有效平均分；
笨方法：
SELECT t1.student_id,t1.sy,t2.ty,t3.wl,t4.avg_scr from

(select student_id,num as sy from score
LEFT JOIN course on score.course_id=course.cid
where cname = '生物') as t1

LEFT JOIN

(select student_id,num as ty from score
LEFT JOIN course on score.course_id=course.cid
where cname = '体育') as t2
on t1.student_id=t2.student_id

LEFT JOIN

(select student_id,num as wl from score
LEFT JOIN course on score.course_id=course.cid
where cname = '物理') as t3
on t1.student_id=t3.student_id
LEFT JOIN

(select student_id,avg(num) as avg_scr from score
LEFT JOIN course on score.course_id=course.cid
where cname in ('物理','体育','生物') GROUP BY student_id) as t4
on t1.student_id=t4.student_id

方案二：
select
student_id,
(select num from score as s2 where s2.student_id=s1.student_id and course_id = 1) as 语文,
(select num from score as s2 where s2.student_id=s1.student_id and course_id = 2) as 数学,
(select num from score as s2 where s2.student_id=s1.student_id and course_id = 3) as 英语,
count(s1.course_id),
avg(s1.num)
from score as s1 group by student_id;



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,max(num)as '最高分',min(num)as '最低分' from score GROUP BY course_id
19按各科平均成绩从低到高和及格率的百分数从高到低顺序

select course_id,avg(num),sum(case when num < 60 then 0 else 1 end)/sum(1) as jgl
from score group by course_id ORDER BY avg(num) asc,jgl desc;

20课程平均分从高到低显示（现实任课老师）
select tname,cname,avg(num) from score
LEFT JOIN course on score.course_id=course.cid
LEFT JOIN teacher on course.cid=teacher.tid
 GROUP BY course_id
21查询各科成绩前三名的记录:(不考虑成绩并列情况)
select course_id,

(select num from score as s2 where s1.course_id=s2.course_id  order by num desc limit 0,1) as first_num,
(select num from score as s2 where s1.course_id=s2.course_id  order by num desc limit 1,1) as second_num,
(select num from score as s2 where s1.course_id=s2.course_id  order by num desc limit 2,1) as third_num
from score as s1 GROUP BY course_id

22、查询每门课程被选修的学生数；
select course_id,count(student_id) from score group by course_id

23、查询出只选修了一门课程的全部学生的学号和姓名；
select student_id,sname from score
 left join student on score.student_id=student.sid
 group by student_id having count(course_id)=1
24、查询男生、女生的人数；
select gender,count(sid) from student group by gender
25、查询姓“张”的学生名单；
select sname from student where sname like '张%'
26、查询同名同姓学生名单，并统计同名人数；
select sname,count(sname) from student group by sname having count(sname)>1
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 avg(num),course_id from score group by course_id order by avg(num) asc,course_id 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_id,sname,avg(num) from score
LEFT JOIN student on score.student_id=student.sid
group by student_id having avg(num)>85
29、查询课程名称为“数学”，且分数低于60的学生姓名和分数；
select sname,num from score
left join student on score.student_id=student.sid
left join course on score.course_id=course.cid
where cname='生物' and num < 60
30、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 student_id,sname from score
left join student on score.student_id=student.sid
where course_id=3 and num > 80
31、求选了课程的学生人数
select count(student_id) from
(select student_id from score group by student_id) as t1
32、查询选修“杨艳”老师所授课程的学生中，成绩最高的学生姓名及其成绩
select student_id,num from score
LEFT JOIN student on score.student_id = student.sid
where course_id in
(select cid from course
left join teacher on course.teacher_id=teacher.tid
where tname='李平老师') ORDER BY num desc limit 1


33、查询各个课程及相应的选修人数；
select course_id,count(student_id) from score group by course_id
34、查询不同课程但成绩相同的学生的学号、课程号、学生成绩；

select DISTINCT s1.course_id,s2.course_id,s1.num,s2.num
from score as s1, score as s2
where s1.num = s2.num and s1.course_id != s2.course_id;

35、查询每门课程成绩最好的前两名； 同21
select course_id,

(select num from score as s2 where s1.course_id=s2.course_id  order by num desc limit 0,1) as first_num,
(select num from score as s2 where s1.course_id=s2.course_id  order by num desc limit 1,1) as second_num
from score as s1 GROUP BY course_id
36、检索至少选修两门课程的学生学号；
select student_id from score
 left join student on score.student_id=student.sid
 group by student_id having count(course_id)> =2
37、查询全部学生都选修的课程的课程号和课程名；
select course_id from score group by course_id having count(1) = select count(sid) from student

38、查询没学过“叶平”老师讲授的任一门课程的学生姓名； 同 6

select student.sid,student.sname from student
where sid not in
(select score.student_id from score where course_id in
(select cid from course left join teacher on course.teacher_id=teacher.tid
where  teacher.tname='李平老师')group by student_id);

39、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(num) from
(select student_id,num from score where student_id in

(select student_id from
(select student_id,course_id,num from score where num < 60)
as A GROUP BY student_id having count(student_id) > 1)

) as B GROUP BY student_id
40、检索“004”课程分数小于60，按分数降序排列的同学学号；
select student_id from
(select student_id,num from score where course_id=4)
as A where num < 60 ORDER BY num desc

41、删除“002”同学的“001”课程的成绩；
delete from score where student_id=2 and course_id=1