sql语句练习

表结构图如下：




创建表和插入数据：

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

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

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

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

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

sql练习：
1、查询所有的课程的名称以及对应的任课老师姓名

select course.cname 课程,teacher.tname 讲师 from course inner join teacher on course.teacher_id=teacher.tid;

2、查询学生表中男女生各有多少人

select gender 性别,count(*) 人数 from student group by gender;

3、查询物理成绩等于100的学生的姓名

select sname 姓名 from student where sid in(select student_id from score inner join course on score.course_id=course.cid where course.cname='物理' and score.num=100);

4、查询平均成绩大于八十分的同学的姓名和平均成绩

select student.sname 姓名,avg(score.num) 平均分 from score left join student on score.student_id=student.sid group by student_id;

5、查询所有学生的学号，姓名，选课数，总成绩

select student.sid 学号,student.sname 姓名,count(score.course_id) 课程数,sum(score.num) 总成绩 from student left join score on student.sid=score.student_id group by student.sid;

6、 查询姓李老师的个数

select tname 姓李的老师 from teacher where tname like "李%";

7、 查询没有报李平老师课的学生姓名

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

8、 查询物理课程比生物课程高的学生的学号

select phy.student_id 学号 from
(select score.student_id,score.num from score
left join course on score.course_id=course.cid
where cname="物理") as phy
inner join
(select score.student_id,score.num from score
left join course on score.course_id=course.cid
where cname="生物") as bio
on phy.student_id=bio.student_id where phy.num>bio.num

9、 查询没有同时选修物理课程和体育课程的学生姓名

select sname 姓名 from student where sid not in
(select student_id from score left join course
on score.course_id=course.cid
where cname="体育" or cname="物理"
group by student_id
having count(course_id)>1)
);

10、查询挂科超过两门(包括两门)的学生姓名和班级

select sname,caption from student inner join class on
student.class_id=class.cid where student.sid in
(select student_id from score where score.num<60
group by student_id
having count(student_id)>=2);

11 、查询选修了所有课程的学生姓名

select sname 姓名 from student where sid in
(select student_id from score
group by student_id
having count(student_id) = (select count(cid) from course));

12、查询李平老师教的课程的所有成绩记录

select course.cname 课程,score.num 成绩 from score inner join course
on course_id=cid
where course_id in
(select cid from course left join teacher on teacher_id=tid
where tname like"李平%");

13、查询全部学生都选修了的课程号和课程名

select cid,cname from course where cid in
(select course_id from score
group by course_id
having count(course_id) = (select count(sid) from student));

14、查询每门课程被选修的次数

select course.cname 课程,count(course_id) 选修次数
from score inner join course on score.course_id=course.cid
group by course_id;

15、查询只选修了一门课程的学生姓名和学号

select sid 学号,sname 姓名 from student
where sid in
(select student_id from score
group by student_id
having count(student_id)=1);

16、查询所有学生考出的成绩并按从高到低排序（成绩去重）

select sname 姓名,sum(num) 总分 from score inner join student
on score.student_id=student.sid
group by student_id
order by sum(num) desc;

17、查询平均成绩大于85的学生姓名和平均成绩

select student.sname 姓名,avg(num) 平均成绩
from student inner join score
on student.sid=student_id
group by student_id
having avg(num)>85;

18、查询生物成绩不及格的学生姓名和对应生物分数

select sname 姓名,num 分数 from score inner join student
on student_id=student.sid
where course_id in (select cid from course
where cname="生物")
having num <60;

19、查询在所有选修了李平老师课程的学生中，这些课程(李平老师的课程，不是所有课程)平均成绩最高的学生姓名

select student.sname 姓名,avg(num) 平均成绩
from score inner join student
on score.student_id=student.sid
where course_id in
(select cid from course inner join teacher
on  teacher_id=tid
where teacher.tname like "李平%" )
group by student_id
order by avg(num) desc
limit 1