Python9-MySQL-Homework-day43

表结构

SET NAMES utf8;
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`
-- ----------------------------
BEGIN;
INSERT INTO `class` VALUES ('1', '三年二班'), ('2', '三年三班'), ('3', '一年二班'), ('4', '二年九班');
COMMIT;

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

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

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

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

SET FOREIGN_KEY_CHECKS = 1;

-- 成绩大于60分
-- select * from score where num >60
-- 课程表中老师任课的个数是多少？
-- SELECT * FROM course;
-- SELECT teacher_id,count(cname)FROM course GROUP BY teacher_id;
-- 查询老师所有的课程；
-- SELECT * FROM course
-- LEFT JOIN teacher on course.teacher_id = teacher.tid;
-- 查看学生班级名称
-- SELECT * FROM student
-- LEFT JOIN class on student.class_id = class.cid;
-- 学生表中男生的个数和女生的个数
-- SELECT gender,count(gender) FROM student GROUP BY gender;
-- 临时表
-- SELECT num,course_id FROM (SELECT * FROM score WHERE num >60) as B;
-- 查询平均成绩大于60分的同学的学号和平均成绩；
-- SELECT student_id,avg(num) FROM score GROUP BY student_id HAVING avg(num) >60;
-- SELECT B.student_id,student.sname,B.ccc FROM (SELECT student_id,avg(num) as ccc FROM score GROUP BY student_id HAVING avg(num) >60) as B LEFT JOIN student on B.student_id = student.sid
-- 查询所有同学的学号、姓名、选课数、总成绩；
-- SELECT score.student_id,student.sname,count(student_id),sum(num) FROM score LEFT JOIN student on score.student_id = student.sid GROUP BY score.student_id
-- 查询没学过“李平”老师课的同学的学号、姓名；
-- SELECT * FROM teacher
-- 李平任教的课程id
-- SELECT course.cid FROM course LEFT JOIN teacher on course.teacher_id = teacher.tid WHERE teacher.tname = "李平老师"
-- SELECT * FROM score WHERE course_id not in (2,4)
-- SELECT student.sid,student.sname FROM student WHERE
-- sid not in (
-- SELECT
-- student_id
-- FROM
-- score
-- WHERE
-- course_id IN ( SELECT course.cid FROM course LEFT JOIN teacher ON course.teacher_id = teacher.tid WHERE teacher.tname = "李平老师" )
-- GROUP BY student_id )
-- 查询“生物”课程比“物理”课程成绩高的所有学生的学号；
-- SELECT score.sid,score.student_id,course.cname,score.num FROM score LEFT JOIN course on score.course_id =course.cid WHERE course.cname = "生物"
-- SELECT score.sid,score.student_id,course.cname,score.num FROM score LEFT JOIN course on score.course_id =course.cid WHERE course.cname = "物理"
-- SELECT A.student_id FROM
-- (SELECT score.sid,score.student_id,course.cname,score.num FROM score LEFT JOIN course on score.course_id =course.cid WHERE course.cname = "生物") as A
-- inner JOIN
-- (SELECT score.sid,score.student_id,course.cname,score.num FROM score LEFT JOIN course on score.course_id =course.cid WHERE course.cname = "物理") as B
-- on A.student_id = B.student_id WHERE A.num > B.num

-- 查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；

-- SELECT
-- score.student_id,student.sname
-- FROM
-- score
-- LEFT JOIN student on score.student_id=student.sid
-- WHERE
-- course_id = 1
-- OR course_id = 2
-- GROUP BY
-- student_id
-- HAVING
-- count( course_id ) >1
-- 查询学过“叶平”老师所教的所有课的同学的学号、姓名；
-- SELECT student_id FROM score WHERE course_id in (
-- SELECT cid FROM course LEFT JOIN teacher on course.teacher_id = teacher.tid WHERE teacher.tname = "李平老师") GROUP BY student_id HAVING count(course_id) =(SELECT count(cid) FROM course LEFT JOIN teacher on course.teacher_id = teacher.tid WHERE teacher.tname = "李平老师")
-- 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；
-- 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 num < 60 )
-- 查询没有学全所有课的同学的学号、姓名；
-- SELECT student_id,count(1) FROM score GROUP BY student_id HAVING count(1)< (SELECT count(1) FROM course)
-- 查询至少学过学号为“001”同学所选课程中任意一门课的其他同学学号和姓名；
-- SELECT course_id FROM score WHERE student_id = 1;
-- SELECT student_id FROM score WHERE student_id !=1 and course_id in (SELECT course_id FROM score WHERE student_id = 1) GROUP BY student_id
-- 查询至少学过学号为“001”同学所选课程中任意一门课的其他同学学号和姓名；
-- SELECT course_id FROM score WHERE student_id = 1;
-- SELECT
-- student_id,
-- count( 1 )
-- FROM
-- score
-- WHERE
-- student_id != 1
-- AND course_id IN ( SELECT course_id FROM score WHERE student_id = 1 )
-- GROUP BY
-- student_id
-- HAVING
-- count( 1 ) = ( SELECT count( course_id ) FROM score WHERE student_id = 1 )

-- 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；
-- SELECT student_id,count(1) FROM score WHERE student_id != 1 GROUP BY student_id HAVING count(1) = (SELECT count(1) FROM score WHERE student_id =1)
-- SELECT * FROM score WHERE student_id in (SELECT student_id FROM score WHERE student_id != 1 GROUP BY student_id HAVING count(1) = (SELECT count(1) FROM score WHERE student_id =1)) and course_id in (SELECT course_id WHERE student_id =1)

-- SELECT student_id FROM score WHERE student_id != 1 GROUP BY student_id HAVING count(1) = (SELECT count(1) FROM score WHERE student_id =1);
-- SELECT student_id FROM score WHERE student_id in( SELECT student_id FROM score WHERE student_id != 1 GROUP BY student_id HAVING count(1) = (SELECT count(1) FROM score WHERE student_id =1)) and course_id in(SELECT course_id FROM score WHERE student_id =1) GROUP BY student_id HAVING count(1) = (SELECT count(1) FROM score WHERE student_id =1)

-- 删除学习“叶平”老师课的SC表记录；
-- 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；
-- SELECT student_id,2,(SELECT avg(num) FROM score WHERE course_id = 2) FROM score WHERE course_id != 2
-- SELECT avg(num) FROM score WHERE course_id = 2;

-- 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
-- student_id,
-- (SELECT num FROM score as s2 WHERE s2.student_id = s1.student_id and course_id = 1) as 语文,
-- (SELECT num FROM score as s2 WHERE s2.student_id = s1.student_id and course_id = 2) as 数学,
-- (SELECT num FROM score as s2 WHERE s2.student_id = s1.student_id and course_id = 3) as 英语
-- FROM score as s1;
-- 查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分；
-- SELECT course_id,max(num),min(num)+1,CASE WHEN min(num)<10 THEN 0 ELSE min(num) END as C FROM score GROUP BY course_id
-- 按各科平均成绩从低到高和及格率的百分数从高到低顺序；
-- SELECT course_id,avg(num),sum(CASE WHEN num <60 THEN 0 ELSE 1 END ),sum(1),sum(CASE WHEN num <60 THEN 0 ELSE 1 END )/sum(1) as jgl FROM score GROUP BY course_id ORDER BY avg(num) asc,jgl desc

-- 课程平均分从高到低显示（现实任课老师）；
-- SELECT score.course_id,avg(if(isnull(score.num),0,score.num)),course.cname,teacher.tname FROM score
-- LEFT JOIN course on score.course_id = course.cid
-- LEFT JOIN teacher on teacher.tid = course.teacher_id
-- GROUP BY score.course_id
-- 查询各科成绩前三名的记录:(不考虑成绩并列情况)
-- SELECT * FROM score WHERE course_id=1 ORDER BY num desc LIMIT 0,3;
-- SELECT num FROM score WHERE course_id=1 GROUP BY num ORDER BY num desc LIMIT 3,1;

-- SELECT * FROM
-- (
-- SELECT
-- course_id,
-- student_id,
-- num,
-- 1,
-- (SELECT num FROM score as s2 WHERE s2.course_id=s1.course_id GROUP BY num ORDER BY num desc LIMIT 0,1),
-- (SELECT num FROM score as s2 WHERE s2.course_id=s1.course_id GROUP BY num ORDER BY num desc LIMIT 3,1) as cc
-- FROM score as s1 ) as B
-- WHERE B.num > B.cc
--
-- 查询每门课程被选修的学生数；

-- SELECT course_id ,count(1) FROM score GROUP BY course_id HAVING count(1) >5
-- 查询出只选修了一门课程的全部学生的学号和姓名
-- SELECT student_id, count(1) FROM score GROUP BY student_id HAVING count(1)=1
-- 查询男生、女生的人数；
-- SELECT gender,count(1) FROM student GROUP BY gender
-- 查询姓“张”的学生名单；like
-- 查询同名同姓学生名单，并统计同名人数；
-- SELECT sname,count(1) FROM student GROUP BY sname;
-- 查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列；
-- 查询平均成绩大于85的所有学生的学号、姓名和平均成绩；
-- 查询课程名称为“数学”，且分数低于60的学生姓名和分数；
-- SELECT cid FROM course WHERE cname='生物'
-- SELECT * FROM score WHERE num < 60 and course_id =(SELECT cid FROM course WHERE cname='生物')
-- SELECT score.student_id,student.sname,score.num FROM score LEFT JOIN course on score.course_id=course.cid
-- LEFT JOIN student on score.student_id = student.sid
-- WHERE score.num < 60 and course.cname='生物'
-- 查询课程编号为003且课程成绩在80分以上的学生的学号和姓名；
-- 求选了课程的学生人数
-- SELECT count(DISTINCT student_id) FROM score
-- 查询选修“杨艳”老师所授课程的学生中，成绩最高的学生姓名及其成绩；
-- 查询各个课程及相应的选修人数；
-- 查询不同课程但成绩相同的学生的学号、课程号、学生成绩；
-- SELECT s1.student_id FROM score as s1,score s2 WHERE s1.sid != s2.sid and s1.course_id != s2.course_id and s1.num = s2.num;
-- 检索至少选修两门课程的学生学号；
-- 查询全部学生都选修的课程的课程号和课程名
-- 查询没学过“叶平”老师讲授的任一门课程的学生姓名；
-- SELECT cid FROM course LEFT JOIN teacher on course.teacher_id= teacher.tid WHERE teacher.tname = '李平老师'
-- SELECT * FROM student WHERE sid not in (
-- SELECT student_id FROM score WHERE course_id in (SELECT cid FROM course LEFT JOIN teacher on course.teacher_id= teacher.tid WHERE teacher.tname = '李平老师'))
-- 查询两门以上不及格课程的同学的学号及其平均成绩
-- 检索“004”课程分数小于60，按分数降序排列的同学学号；
-- 删除“002”同学的“001”课程的成绩；

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原文地址：https://www.cnblogs.com/zhangtengccie/p/10459602.html