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MYSQL 练习

时间：2021-07-01 10:21:17 帮助过：4人阅读

Navicat MySQL Data Transfer Source Server : abc Source Server Version : 50713 Source Host : localhost:3306 Source Database : lx Target Server Type : MYSQL Target Server Version : 50713 File Encoding : 65001 Date: 2016-10-24 18:07:25 */ 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(20) DEFAULT 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‘, ‘一年三班‘); INSERT INTO `class` VALUES (‘3‘, ‘三年一班‘); INSERT INTO `class` VALUES (‘4‘, ‘python 二期‘); -- ---------------------------- -- Table structure for `course` -- ---------------------------- DROP TABLE IF EXISTS `course`; CREATE TABLE `course` ( `cid` int(11) NOT NULL AUTO_INCREMENT, `cname` varchar(20) DEFAULT NULL, `teache_id` int(11) DEFAULT NULL, PRIMARY KEY (`cid`), KEY `fk_c_t` (`teache_id`), CONSTRAINT `fk_c_t` FOREIGN KEY (`teache_id`) REFERENCES `teacher` (`tid`) ) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of course -- ---------------------------- INSERT INTO `course` VALUES (‘1‘, ‘生物‘, ‘1‘); INSERT INTO `course` VALUES (‘2‘, ‘体育‘, ‘1‘); INSERT INTO `course` VALUES (‘3‘, ‘物理‘, ‘2‘); -- ---------------------------- -- Table structure for `score` -- ---------------------------- DROP TABLE IF EXISTS `score`; CREATE TABLE `score` ( `sid` int(11) NOT NULL AUTO_INCREMENT, `student_id` int(11) DEFAULT NULL, `corse_id` int(11) DEFAULT NULL, `number` int(11) DEFAULT NULL, PRIMARY KEY (`sid`), KEY `fk_s_st` (`student_id`), KEY `fk_s_co` (`corse_id`), CONSTRAINT `fk_s_co` FOREIGN KEY (`corse_id`) REFERENCES `course` (`cid`), CONSTRAINT `fk_s_st` FOREIGN KEY (`student_id`) REFERENCES `student` (`sid`) ) ENGINE=InnoDB AUTO_INCREMENT=33 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of score -- ---------------------------- INSERT INTO `score` VALUES (‘1‘, ‘1‘, ‘1‘, ‘60‘); INSERT INTO `score` VALUES (‘2‘, ‘1‘, ‘2‘, ‘59‘); INSERT INTO `score` VALUES (‘3‘, ‘2‘, ‘2‘, ‘100‘); INSERT INTO `score` VALUES (‘4‘, ‘1‘, ‘3‘, ‘76‘); INSERT INTO `score` VALUES (‘5‘, ‘2‘, ‘1‘, ‘99‘); INSERT INTO `score` VALUES (‘6‘, ‘2‘, ‘3‘, ‘88‘); INSERT INTO `score` VALUES (‘7‘, ‘3‘, ‘1‘, ‘66‘); INSERT INTO `score` VALUES (‘8‘, ‘3‘, ‘2‘, ‘77‘); INSERT INTO `score` VALUES (‘9‘, ‘3‘, ‘3‘, ‘88‘); INSERT INTO `score` VALUES (‘10‘, ‘4‘, ‘1‘, ‘76‘); INSERT INTO `score` VALUES (‘11‘, ‘4‘, ‘2‘, ‘99‘); INSERT INTO `score` VALUES (‘12‘, ‘4‘, ‘3‘, ‘88‘); INSERT INTO `score` VALUES (‘13‘, ‘5‘, ‘1‘, ‘66‘); INSERT INTO `score` VALUES (‘14‘, ‘5‘, ‘2‘, ‘77‘); INSERT INTO `score` VALUES (‘15‘, ‘5‘, ‘3‘, ‘88‘); INSERT INTO `score` VALUES (‘16‘, ‘6‘, ‘1‘, ‘58‘); INSERT INTO `score` VALUES (‘17‘, ‘6‘, ‘2‘, ‘68‘); INSERT INTO `score` VALUES (‘18‘, ‘6‘, ‘3‘, ‘78‘); INSERT INTO `score` VALUES (‘19‘, ‘7‘, ‘1‘, ‘87‘); INSERT INTO `score` VALUES (‘20‘, ‘7‘, ‘2‘, ‘76‘); INSERT INTO `score` VALUES (‘21‘, ‘7‘, ‘3‘, ‘65‘); INSERT INTO `score` VALUES (‘22‘, ‘8‘, ‘1‘, ‘90‘); INSERT INTO `score` VALUES (‘23‘, ‘8‘, ‘2‘, ‘81‘); INSERT INTO `score` VALUES (‘24‘, ‘8‘, ‘3‘, ‘77‘); INSERT INTO `score` VALUES (‘25‘, ‘9‘, ‘1‘, ‘86‘); INSERT INTO `score` VALUES (‘26‘, ‘9‘, ‘2‘, ‘78‘); INSERT INTO `score` VALUES (‘27‘, ‘9‘, ‘3‘, ‘97‘); -- ---------------------------- -- Table structure for `student` -- ---------------------------- DROP TABLE IF EXISTS `student`; CREATE TABLE `student` ( `sid` int(11) NOT NULL AUTO_INCREMENT, `sname` varchar(20) DEFAULT NULL, `gender` varchar(12) DEFAULT NULL, `class_id` int(11) DEFAULT NULL, PRIMARY KEY (`sid`), KEY `fk_s_c` (`class_id`), CONSTRAINT `fk_s_c` FOREIGN KEY (`class_id`) REFERENCES `class` (`cid`) ) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of student -- ---------------------------- INSERT INTO `student` VALUES (‘1‘, ‘钢蛋‘, ‘女‘, ‘1‘); INSERT INTO `student` VALUES (‘2‘, ‘铁锤‘, ‘女‘, ‘1‘); INSERT INTO `student` VALUES (‘3‘, ‘山炮‘, ‘男‘, ‘2‘); INSERT INTO `student` VALUES (‘4‘, ‘张三‘, ‘男‘, ‘3‘); INSERT INTO `student` VALUES (‘5‘, ‘李四‘, ‘男‘, ‘2‘); INSERT INTO `student` VALUES (‘6‘, ‘王五‘, ‘男‘, ‘3‘); INSERT INTO `student` VALUES (‘7‘, ‘马六‘, ‘女‘, ‘1‘); INSERT INTO `student` VALUES (‘8‘, ‘霍七‘, ‘男‘, ‘2‘); INSERT INTO `student` VALUES (‘9‘, ‘贺八‘, ‘男‘, ‘3‘); -- ---------------------------- -- Table structure for `teacher` -- ---------------------------- DROP TABLE IF EXISTS `teacher`; CREATE TABLE `teacher` ( `tid` int(11) NOT NULL AUTO_INCREMENT, `tname` varchar(20) DEFAULT NULL, PRIMARY KEY (`tid`) ) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of teacher -- ---------------------------- INSERT INTO `teacher` VALUES (‘1‘, ‘波多‘); INSERT INTO `teacher` VALUES (‘2‘, ‘苍空‘); INSERT INTO `teacher` VALUES (‘3‘, ‘饭岛‘); 创建表（结构）

2、查询“生物”课程比“物理”课程成绩高的所有学生的学号；

思路： 获取所有有生物课程的人（学号，成绩） - 临时表 获取所有有物理课程的人（学号，成绩） - 临时表 根据【学号】连接两个临时表： 学号物理成绩生物成绩 然后再进行筛选

select A.student_id,生物,物理 from
 
        (select student_id,number as 生物 from score left join course on score.corse_id = course.cid where course.cname = ‘生物‘) as A
 
        left join
 
        (select student_id,number  as 物理 from score left join course on score.corse_id = course.cid where course.cname = ‘物理‘) as B
 
        on A.student_id = B.student_id where 物理 >  生物 ;

3、查询平均成绩大于60分的同学的学号和平均成绩； 思路： 根据学生分组，使用avg获取平均值，通过having对avg进行筛选

select student_id,avg(number) from score GROUP BY student_id having avg(number)>60;

4、查询所有同学的学号、姓名、选课数、总成绩；

SELECT
    score.student_id,
    COUNT(score.corse_id),
    SUM(score.number),
    student.sname
FROM
    score
LEFT JOIN student ON student.sid = score.student_id
GROUP BY
    student_id

5、查询姓“李”的老师的个数

select COUNT(tid) from teacher where tname LIKE"波%";

select count(1) from (select tid from teacher where tname like ‘波%‘) as B

6、查询没学过“叶平”老师课的同学的学号、姓名； 思路： 先查到“叶平老师”老师教的所有课ID 获取选过课的所有学生ID 学生表中筛选

select * from student where sid not in(
select student_id from score WHERE score.corse_id in(
select cid from course 
LEFT JOIN teacher on teacher.tid = course.teache_id where teacher.tname = "波多"
)
)

7、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名； 思路： 先查到既选择001又选择002课程的所有同学 根据学生进行分组，如果学生数量等于2表示，两门均已选择

 select student_id,sname from
 
    (select student_id,corse_id from score where corse_id = 1 or corse_id = 2) as B
      
    left join student on B.student_id = student.sid group by student_id HAVING count(student_id) = 2

8、查询学过“叶平”老师所教的所有课的同学的学号、姓名；

select * from student where sid  in(
select student_id from score WHERE score.corse_id in(
select cid from course 
LEFT JOIN teacher on teacher.tid = course.teache_id where teacher.tname = "波多"
)
)

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；

select c.student_id,student.sname from
(select A.student_id,a,b from
 
        (select student_id,number as a from score left join course on score.corse_id = course.cid where course.cid = 1) as A
 
        left join
 
        (select student_id,number  as b from score left join course on score.corse_id = course.cid where course.cid = 2) as B
        on A.student_id = B.student_id where b >  a ) as c
         LEFT JOIN
       student on c.student_id = student.sid;

10、查询有课程成绩小于60分的同学的学号、姓名；

select sid,sname from student where sid in (
        select distinct student_id from score where number < 60
    )

select sid,sname from student where sid in (
        select  student_id from score where number < 60 GROUP BY student_id
    )

11、查询没有学全所有课的同学的学号、姓名； 思路： 在分数表中根据学生进行分组，获取每一个学生选课数量 如果数量 == 总课程数量，表示已经选择了所有课程

 select student_id,sname from score left join student on score.student_id = student.sid
        group by student_id HAVING count(corse_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； 思路： 获取 001 同学选择的所有课程 获取课程在其中的所有人以及所有课程 根据学生筛选，获取所有学生信息 再与学生表连接，获取姓名

select student_id,sname, count(corse_id)
        from score left join student on score.student_id = student.sid
        where student_id != 1 and corse_id in (select corse_id from score where 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； 先找到和001的学过的所有人 然后个数＝ 001所有学科＝＝》其他人可能选择的更多

 select student_id,sname, count(corse_id)
        from score left join student on score.student_id = student.sid
        where student_id != 1 and corse_id in (select corse_id from score where student_id = 1) 
group by student_id

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； 个数相同 002学过的也学过

select student_id,sname from score left join student on score.student_id = student.sid where student_id in (
            select student_id from score  where student_id != 1 group by student_id HAVING count(corse_id) = (select count(1) from score where student_id = 1)
        ) and corse_id in (select corse_id from score where student_id = 1) group by student_id HAVING count(corse_id) = (select count(1) from score where student_id = 1)

15、删除学习“叶平”老师课的score表记录；

delete from score where corse_id in (
        select cid from course left join teacher on course.teache_id = teacher.tid where teacher.tname = ‘饭岛‘
    )

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, corse_id, number) select sid,2,(select avg(number) from score where corse_id = 2)
    from student where sid not in (
        select student_id from score where corse_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；

 select sc.student_id,
        (select number from score left join course on score.corse_id = course.cid where course.cname = "生物" and score.student_id=sc.student_id) as sy,
        (select number from

                  

	 	
                    
                        
                            
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