表結構圖如下：

創建表和插入數據：

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‘, ‘體育‘, ‘3‘);
INSERT INTO `course` VALUES (‘4‘, ‘美術‘, ‘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‘, ‘鋼蛋‘);
INSERT INTO `student` VALUES (‘3‘, ‘男‘, ‘1‘, ‘張三‘);
INSERT INTO `student` VALUES (‘4‘, ‘男‘, ‘1‘, ‘張一‘);
INSERT INTO `student` VALUES (‘5‘, ‘女‘, ‘1‘, ‘張二‘);
INSERT INTO `student` VALUES (‘6‘, ‘男‘, ‘1‘, ‘張四‘);
INSERT INTO `student` VALUES (‘7‘, ‘女‘, ‘2‘, ‘鐵錘‘);
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‘, ‘劉三‘);
INSERT INTO `student` VALUES (‘14‘, ‘男‘, ‘3‘, ‘劉一‘);
INSERT INTO `student` VALUES (‘15‘, ‘女‘, ‘3‘, ‘劉二‘);
INSERT INTO `student` VALUES (‘16‘, ‘男‘, ‘3‘, ‘劉四‘);

-- ----------------------------
-- 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‘, ‘張磊老師‘);
INSERT INTO `teacher` VALUES (‘2‘, ‘李平老師‘);
INSERT INTO `teacher` VALUES (‘3‘, ‘劉海燕老師‘);
INSERT INTO `teacher` VALUES (‘4‘, ‘朱雲海老師‘);
INSERT INTO `teacher` VALUES (‘5‘, ‘李傑老師‘);
SET FOREIGN_KEY_CHECKS=1;

sql練習：

1、查詢所有的課程的名稱以及對應的任課老師姓名

select course.cname 課程,teacher.tname 講師 from course inner join teacher on course.teacher_id=teacher.tid;

2、查詢學生表中男女生各有多少人

select gender 性別,count(*) 人數 from student group by gender;

3、查詢物理成績等於100的學生的姓名

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、查詢平均成績大於八十分的同學的姓名和平均成績

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、查詢所有學生的學號，姓名，選課數，總成績

select student.sid 學號,student.sname 姓名,count(score.course_id) 課程數,sum(score.num) 總成績 from student left join score on student.sid=score.student_id group by student.sid;

6、 查詢姓李老師的個數

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

7、 查詢沒有報李平老師課的學生姓名

select sid 學號,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="李平老師"));

8、 查詢物理課程比生物課程高的學生的學號

select phy.student_id 學號 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、 查詢沒有同時選修物理課程和體育課程的學生姓名

 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="體育" or cname="物理"
	group by student_id
	having count(course_id)>1)
);

10、查詢掛科超過兩門(包括兩門)的學生姓名和班級

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 、查詢選修了所有課程的學生姓名

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、查詢李平老師教的課程的所有成績記錄

select course.cname 課程,score.num 成績 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、查詢全部學生都選修了的課程號和課程名

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、查詢每門課程被選修的次數

select course.cname 課程,count(course_id) 選修次數 
from score inner join course on score.course_id=course.cid
group by course_id;

15、查詢只選修了一門課程的學生姓名和學號

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

16、查詢所有學生考出的成績並按從高到低排序（成績去重）

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

17、查詢平均成績大於85的學生姓名和平均成績

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

18、查詢生物成績不及格的學生姓名和對應生物分數

select sname 姓名,num 分數 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、查詢在所有選修了李平老師課程的學生中，這些課程(李平老師的課程，不是所有課程)平均成績最高的學生姓名

select student.sname 姓名,avg(num) 平均成績 
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

本文出自 “lyndon” 博客，請務必保留此出處http://lyndon.blog.51cto.com/11474010/1965155

sql語句練習