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=;

-- ----------------------------

-- Table structure for class

-- ----------------------------

DROP TABLE IF EXISTS `class`;

CREATE TABLE `class` (

  `cid` int() NOT NULL AUTO_INCREMENT,

  `caption` varchar() NOT NULL,

  PRIMARY KEY (`cid`)

) ENGINE=InnoDB AUTO_INCREMENT= DEFAULT CHARSET=utf8;

-- ----------------------------

-- Records of class

-- ----------------------------

INSERT INTO `class` VALUES ('', '三年二班');

INSERT INTO `class` VALUES ('', '三年三班');

INSERT INTO `class` VALUES ('', '一年二班');

INSERT INTO `class` VALUES ('', '二年九班');

-- ----------------------------

-- Table structure for course

-- ----------------------------

DROP TABLE IF EXISTS `course`;

CREATE TABLE `course` (

  `cid` int() NOT NULL AUTO_INCREMENT,

  `cname` varchar() NOT NULL,

  `teacher_id` int() 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= DEFAULT CHARSET=utf8;

-- ----------------------------

-- Records of course

-- ----------------------------

INSERT INTO `course` VALUES ('', '生物', '');

INSERT INTO `course` VALUES ('', '物理', '');

INSERT INTO `course` VALUES ('', '体育', '');

INSERT INTO `course` VALUES ('', '美术', '');

-- ----------------------------

-- Table structure for score

-- ----------------------------

DROP TABLE IF EXISTS `score`;

CREATE TABLE `score` (

  `sid` int() NOT NULL AUTO_INCREMENT,

  `student_id` int() NOT NULL,

  `course_id` int() NOT NULL,

  `num` int() 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= DEFAULT CHARSET=utf8;

-- ----------------------------

-- Records of score

-- ----------------------------

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

INSERT INTO `score` VALUES ('', '', '', '');

-- ----------------------------

-- Table structure for student

-- ----------------------------

DROP TABLE IF EXISTS `student`;

CREATE TABLE `student` (

  `sid` int() NOT NULL AUTO_INCREMENT,

  `gender` char() NOT NULL,

  `class_id` int() NOT NULL,

  `sname` varchar() NOT NULL,

  PRIMARY KEY (`sid`),

  KEY `fk_class` (`class_id`),

  CONSTRAINT `fk_class` FOREIGN KEY (`class_id`) REFERENCES `class` (`cid`)

) ENGINE=InnoDB AUTO_INCREMENT= DEFAULT CHARSET=utf8;

-- ----------------------------

-- Records of student

-- ----------------------------

INSERT INTO `student` VALUES ('', '男', '', '理解');

INSERT INTO `student` VALUES ('', '女', '', '钢蛋');

INSERT INTO `student` VALUES ('', '男', '', '张三');

INSERT INTO `student` VALUES ('', '男', '', '张一');

INSERT INTO `student` VALUES ('', '女', '', '张二');

INSERT INTO `student` VALUES ('', '男', '', '张四');

INSERT INTO `student` VALUES ('', '女', '', '铁锤');

INSERT INTO `student` VALUES ('', '男', '', '李三');

INSERT INTO `student` VALUES ('', '男', '', '李一');

INSERT INTO `student` VALUES ('', '女', '', '李二');

INSERT INTO `student` VALUES ('', '男', '', '李四');

INSERT INTO `student` VALUES ('', '女', '', '如花');

INSERT INTO `student` VALUES ('', '男', '', '刘三');

INSERT INTO `student` VALUES ('', '男', '', '刘一');

INSERT INTO `student` VALUES ('', '女', '', '刘二');

INSERT INTO `student` VALUES ('', '男', '', '刘四');

-- ----------------------------

-- Table structure for teacher

-- ----------------------------

DROP TABLE IF EXISTS `teacher`;

CREATE TABLE `teacher` (

  `tid` int() NOT NULL AUTO_INCREMENT,

  `tname` varchar() NOT NULL,

  PRIMARY KEY (`tid`)

) ENGINE=InnoDB AUTO_INCREMENT= DEFAULT CHARSET=utf8;

-- ----------------------------

-- Records of teacher

-- ----------------------------

INSERT INTO `teacher` VALUES ('', '张磊老师');

INSERT INTO `teacher` VALUES ('', '李平老师');

INSERT INTO `teacher` VALUES ('', '刘海燕老师');

INSERT INTO `teacher` VALUES ('', '朱云海老师');

INSERT INTO `teacher` VALUES ('', '李杰老师');

SET FOREIGN_KEY_CHECKS=;

创建表和插入数据

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,

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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

查询条件

MySQL数据库--练习的更多相关文章

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