MySQL数据库--练习
学生选课系统
设计表关系
创建表和插入数据
/* Navicat MySQL Data Transfer Source Server : localhost_3306 Source Server Version : 50719 Source Host : localhost:3306 Source Database : oldbo Target Server Type : MYSQL Target Server Version : 50719 File Encoding : 65001 Date: 2017-07-26 15:46:16 */ 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;
查询条件
-- -- 1、将所有的课程的名称以及对应的任课老师姓名打印出来
SELECT cname,tname 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,COUNT(sid ) FROM student GROUP BY gender;
-- -- 3、查询物理成绩等于100的学生的姓名
-- -- 查询物理课程cid：SELECT cid FROM course WHERE cname='物理'
-- -- SELECT sid,sname FROM student WHERE sid in (SELECT student_id FROM score
-- -- WHERE course_id=(SELECT cid FROM course WHERE cname='物理') AND num=100)
-- -- 简化
SELECT sid,sname FROM student WHERE sid in (SELECT student_id FROM score WHERE course_id=2 AND 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_id,sname,avg(num) FROM score INNER JOIN student on score.student_id=student.sid GROUP BY student_id HAVING avg(num)>80;
-- -- 5、查询所有学生的学号，姓名，选课数，总成绩
SELECT student_id,sname,COUNT(course_id) 选课数, SUM(num) 总成绩 FROM score INNER JOIN student on score.student_id=student.sid GROUP BY student_id ;
-- -- 6、查询姓李老师的个数
SELECT COUNT(tname) FROM teacher WHERE tname LIKE '李%';
-- -- 7、查询没有报李平老师课的学生姓名
-- -- 李平老师的tid：SELECT tid FROM teacher WHERE tname='李平老师';
-- -- 李平老师的课程cid：(2,4) SELECT cid FROM course WHERE teacher_id =(SELECT tid FROM teacher WHERE tname='李平老师');
-- -- 选了李平老师课程的学生id：
SELECT DISTINCT student_id FROM score WHERE course_id in
(SELECT cid FROM course WHERE teacher_id =(SELECT tid FROM teacher WHERE tname LIKE '李平%'));
-- -- 简化
SELECT sid,sname FROM student WHERE sid NOT in (
SELECT DISTINCT student_id FROM score WHERE course_id in (2,4));
-- -- 方法二：
SELECT student.sid,sname from student left JOIN score on student.sid=score.student_id
WHERE student.sid NOT IN (SELECT DISTINCT student_id from score where course_id = 2 or course_id=4);
-- 8、查询物理课程比生物课程高的学生的学号
-- 物理表：SELECT student_id,num FROM score WHERE course_id=2;
-- 生物表：SELECT student_id,num FROM score WHERE course_id=1;
--
SELECT phy.student_id resid,phy.num phy,bio.num bio FROM
(SELECT student_id,num FROM score WHERE course_id=2) AS phy
INNER JOIN
(SELECT student_id,num FROM score WHERE course_id=1) AS bio
on phy.student_id=bio.student_id WHERE phy.num>bio.num;
SELECT sid,sname,res.phy,res.bio FROM student
INNER JOIN (
SELECT phy.student_id resid,phy.num phy,bio.num bio FROM
(SELECT student_id,num FROM score WHERE course_id=2) AS phy
INNER JOIN
(SELECT student_id,num FROM score WHERE course_id=1) AS bio
on phy.student_id=bio.student_id WHERE phy.num>bio.num) AS res
ON student.sid=res.resid;
-- -- 9、查询没有同时选修物理课程和体育课程的学生姓名
SELECT sid,sname FROM student WHERE sid NOT in (
SELECT phy.student_id FROM (SELECT student_id FROM score WHERE course_id=2) as phy INNER JOIN (SELECT student_id FROM score WHERE course_id=3) as spo ON phy.student_id=spo.student_id);
-- 方法二
SELECT sid,sname FROM student WHERE sid NOT in (
SELECT student_id FROM (SELECT student_id FROM score WHERE course_id=2) as phy WHERE phy.student_id in (SELECT student_id FROM score WHERE course_id=3));
-- 10、查询挂科超过两门(包括两门)的学生姓名和班级
SELECT sid,sname,caption FROM student INNER JOIN class ON student.class_id=class.cid WHERE sid in (
SELECT student_id FROM score WHERE num<60 GROUP BY student_id HAVING count(sid)>=2 );
-- 11 、查询选修了所有课程的学生姓名
SELECT sid,sname FROM student WHERE sid in (
SELECT student_id FROM score GROUP BY student_id HAVING COUNT(course_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_id,num FROM score WHERE course_id in (
SELECT cid FROM course WHERE teacher_id =(SELECT tid FROM teacher WHERE tname='李平老师')
) ORDER BY course_id;
SELECT tid,tname,cid,cname,res.student_id,student.sname,course_id,num FROM (
SELECT tid,tname,cid,cname,student_id,course_id,num FROM (SELECT tid,tname,cid,cname FROM teacher INNER JOIN course on teacher.tid=course.teacher_id WHERE tname='李平老师') as tea
RIGHT JOIN (SELECT student_id,course_id,num FROM score WHERE course_id in (
SELECT cid FROM course WHERE teacher_id =(SELECT tid FROM teacher WHERE tname='李平老师')
) ORDER BY course_id) as cor ON tea.cid=cor.course_id) AS res INNER JOIN student ON res.student_id=student.sid;
-- 13、查询全部学生都选修了的课程号和课程名
SELECT cid,cname FROM course INNER JOIN (
SELECT course_id FROM score GROUP BY course_id HAVING COUNT(student_id)=(SELECT COUNT(sid) FROM student )) as res on course.cid=res.course_id;
SELECT course_id,COUNT(student_id) FROM score GROUP BY course_id;
SELECT student_id,COUNT(course_id) FROM score GROUP BY student_id;
SELECT count(DISTINCT student_id) FROM score;
-- 14、查询每门课程被选修的次数
SELECT course_id,cname,COUNT(student_id) FROM score INNER JOIN course on score.course_id=course.cid GROUP BY course_id
-- 15、查询之选修了一门课程的学生姓名和学号
SELECT sid,sname FROM student WHERE sid in (
SELECT student_id FROM score GROUP BY student_id HAVING COUNT(course_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 DISTINCT num FROM score ORDER BY num DESC
-- 17、查询平均成绩大于85的学生姓名和平均成绩
SELECT student_id,sname,AVG(num) FROM score INNER JOIN student on score.student_id=student.sid 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 student_id,sname,cname,num FROM (
SELECT student_id,cname,num FROM score INNER JOIN course on score.course_id=course.cid WHERE cname='生物' AND num<60) AS res
INNER JOIN
student
ON student.sid=res.student_id
-- 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 res.student_id,sname,avg(num) FROM (
SELECT student_id,num FROM score WHERE course_id in (2,4)) as res
INNER JOIN
student
on res.student_id=student.sid
GROUP BY res.student_id ORDER BY avg(num) DESC LIMIT 1
-- 20、查询每门课程成绩最好的前两名学生姓名
SELECT student_id,num FROM score WHERE course_id=2 ORDER BY num DESC LIMIT 2
-- 21、查询不同课程但成绩相同的学号，课程号，成绩
-- 22、查询没学过“李平”老师课程的学生姓名以及选修的课程名称；
select res.id,sname,cname FROM course INNER JOIN
(
select student.sid id,sname,course_id FROM student INNER JOIN score ON student.sid=score.student_id
WHERE course_id NOT in(select cid FROM teacher INNER JOIN course on teacher.tid=course.teacher_id WHERE tname LIKE '李平%')
) AS res
ON course.cid=res.course_id
-- 23、查询所有选修了学号为1的同学选修过的一门或者多门课程的同学学号和姓名；
SELECT sid,sname FROM student WHERE sid in (
SELECT DISTINCT student_id FROM score WHERE course_id in (SELECT course_id FROM score WHERE student_id=1)
);
-- 24、任课最多的老师中学生单科成绩最高的学生姓名
# SELECT teacher_id,count(cid) FROM course GROUP BY teacher_id
-- -- 10、查询有课程成绩小于60分的同学的学号、姓名
SELECT sid,sname,course_id,num FROM student INNER JOIN (
SELECT student_id,course_id,num FROM score WHERE num<60) AS res ON student.sid=res.student_id;
/* Navicat MySQL Data Transfer Source Server : localhost_3306 Source Server Version : 50719 Source Host : localhost:3306 Source Database : oldbo Target Server Type : MYSQL Target Server Version : 50719 File Encoding : 65001 Date: 2017-07-26 15:46:16 */ 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,
