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Date: Sun, 22 Oct 2023 22:06:23 +0800
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+# 作业
+
+```mysql
+CREATE DATABASE tt charset utf8;
+use tt;
+# 学生表
+CREATE TABLE IF NOT EXISTS `student`(
+    `student_id` INT(10) NOT NULL AUTO_INCREMENT COMMENT '学号',
+    `student_name` VARCHAR(10) NOT NULL DEFAULT '匿名' COMMENT '姓名',
+    `birthday` DATETIME NOT NULL COMMENT '出生日期',
+    `gender` VARCHAR(10) NOT NULL DEFAULT '男' COMMENT '性别',
+    PRIMARY KEY(`student_id`)
+)ENGINE=INNODB CHARSET=utf8;
+
+INSERT INTO `student` VALUES
+(1 , '赵雷' , '1990-01-01' , '男'),
+(2 , '钱电' , '1990-12-21' , '男'),
+(3 , '孙风' , '1990-12-20' , '男'),
+(4 , '李云' , '1990-12-06' , '男'),
+(5 , '周梅' , '1991-12-01' , '女'),
+(6 , '吴兰' , '1992-01-01' , '女'),
+(7 , '郑竹' , '1989-01-01' , '女'),
+(8 , '张三' , '2017-12-20' , '女'),
+(9 , '李四' , '2017-12-25' , '女'),
+(10 , '李四' , '2012-06-06' , '女'),
+(11 , '赵六' , '2013-06-13' , '女'),
+(12 , '孙七' , '2014-06-01' , '女');
+-- 课程表
+CREATE TABLE IF NOT EXISTS `course`(
+    `course_id` INT(4) NOT NULL AUTO_INCREMENT COMMENT '课程编号',
+    `course_name` VARCHAR(10) NOT NULL COMMENT '课程名',
+    `teacher_id` INT(10) NOT NULL COMMENT '任课教师工号',
+    PRIMARY KEY(`course_id`)
+)ENGINE=INNODB CHARSET=utf8;
+ 
+INSERT INTO `course` VALUES
+(1, '语文', 2),
+(2, '数学', 1),
+(3, '英语', 3);
+# 教师表
+CREATE TABLE IF NOT EXISTS `teacher`(
+    `teacher_id` INT(10) NOT NULL AUTO_INCREMENT COMMENT '教师工号',
+    `teacher_name` VARCHAR(10) NOT NULL DEFAULT '匿名' COMMENT '教师姓名',
+    PRIMARY KEY(`teacher_id`)
+)ENGINE=INNODB CHARSET=utf8;
+ 
+INSERT INTO `teacher` VALUES
+(1, '高斯'),
+(2, '李白'),
+(3, 'Trump');
+
+-- 成绩表
+CREATE TABLE IF NOT EXISTS `score`(
+    `student_id` INT(10) NOT NULL COMMENT '学号',
+    `course_id` INT(4) NOT NULL COMMENT '课程编号',
+    `score` DECIMAL(18,1) COMMENT '成绩',
+    KEY(`course_id`)
+)ENGINE=INNODB CHARSET=utf8;
+ 
+INSERT INTO `score` VALUES
+(1 , 1 , 80),
+(1 , 2 , 90),
+(1 , 3 , 99),
+(2 , 1 , 70),
+(2 , 2 , 60),
+(2 , 3 , 80),
+(3 , 1 , 80),
+(3 , 2 , 80),
+(3 , 3 , 80),
+(4 , 1 , 50),
+(4 , 2 , 30),
+(4 , 3 , 20),
+(5 , 1 , 76),
+(5 , 2 , 87),
+(6 , 1 , 31),
+(6 , 3 , 34),
+(7 , 2 , 89),
+(7 , 3 , 98);
+
+
+-- 1. 查询" 1 "课程比" 2 "课程成绩高的学生的信息（学号、姓名、性别、出生日期）及课程分数
+WITH a AS(SELECT s.student_id,s.student_name,s.gender,s.birthday,c.course_id,c.score from student s,score c WHERE s.student_id=c.student_id and c.course_id=1),
+     b AS(SELECT s.student_id,s.student_name,s.gender,s.birthday,c.course_id,c.score from student s,score c WHERE s.student_id=c.student_id and c.course_id=2)
+SELECT * from a,b where a.student_id=b.student_id and a.score>b.score;
+
+-- 2. 查询同时参与" 1 "课程和" 2 "课程考试的学生信息
+WITH a AS (SELECT s.student_id,s.student_name,s.birthday,s.gender,c.course_id,c.score from student s, score c WHERE s.student_id=c.student_id and course_id=1),
+     b as  (SELECT s.student_id,s.student_name,s.birthday,s.gender,c.course_id,c.score from student s, score c WHERE s.student_id=c.student_id and course_id=2)
+SELECT * from a,b WHERE a.student_id=b.student_id;
+-- 3. 查询存在" 1 "课程但可能不存在" 2 "课程的情况(不存在时显示为 null )
+WITH a AS (SELECT s.student_id,s.student_name,s.birthday,s.gender,c.course_id,c.score from student s, score c WHERE s.student_id=c.student_id and course_id=1),
+     b as  (SELECT s.student_id,s.student_name,s.birthday,s.gender,c.course_id,c.score from student s, score c WHERE s.student_id=c.student_id and course_id=2)
+SELECT * from a left JOIN b on a.student_id=b.student_id where b.gender is null;
+
+-- 4. 查询不存在" 1 "课程但存在" 2 "课程的情况
+WITH a AS (SELECT s.student_id,s.student_name,s.birthday,s.gender,c.course_id,c.score from student s, score c WHERE s.student_id=c.student_id and course_id=1),
+     b as  (SELECT s.student_id,s.student_name,s.birthday,s.gender,c.course_id,c.score from student s, score c WHERE s.student_id=c.student_id and course_id=2)
+SELECT * from a RIGHT JOIN b on a.student_id=b.student_id where a.gender is null;
+-- 5. 查询平均成绩大于等于 60 分的同学的学生编号、姓名和平均成绩
+SELECT DISTINCT s.student_id,s.student_name,avg(score) over(PARTITION by s.student_id) from student s ,score c WHERE s.student_id=c.student_id and score>60;
+-- 6. 查询在成绩表存在成绩的学生信息
+SELECT * from student s LEFT JOIN score c on s.student_id=c.student_id WHERE c.score is not null ;
+-- 7. 查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩(没成绩的显示为 null )
+SELECT s.student_id,s.student_name,COUNT(c.course_id) over(PARTITION BY s.student_id) ,SUM(score) over(PARTITION by s.student_id)  from student s LEFT JOIN score c on s.student_id=c.student_id;
+-- 8. 查询「李」姓老师的数量
+SELECT COUNT(teacher_name) from teacher WHERE teacher_name LIKE'李%';
+-- 9. 查询学过「李白」老师授课的同学的信息
+SELECT * from student s,course c,teacher t,score r WHERE s.student_id=r.student_id and c.teacher_id=t.teacher_id and c.course_id=r.course_id and t.teacher_name='李白';
+-- 10. 查询没有学全所有课程的同学的信息
+SELECT *, COUNT(s.student_id) over(PARTITION by s.student_id),sum(c.course_id) over(PARTITION by s.student_id)  from student s LEFT JOIN score c on s.student_id=c.student_id WHERE score is null;
+-- 11. 查询至少有一门课与学号为" 1 "的同学所学相同的同学的信息
+select * from student,score where student.student_id=score.student_id and course_id in(
+select course_id from student,score where student.student_id=score.student_id and student.student_id=1);
+-- 12. 查询和" 1 "号的同学学习的课程完全相同的其他同学的信息
+with aa as 
+(select distinct student.student_id,student.student_name,sum(score.course_id) over (partition by student.student_id ) 课程编号和 from student,score where student.student_id=score.student_id) 
+select aa.student_id,aa.student_name from aa where 课程编号和=(select sum(course_id) from student,score where student.student_id=score.student_id and student.student_id=1 and aa.student_id!=1);
+-- 13. 查询没学过「李白」老师讲授的任一门课程的学生姓名
+select distinct student.student_name from student,score,course,teacher where student.student_id=score.student_id and score.course_id=course.course_id and course.teacher_id=teacher.teacher_id and teacher.teacher_name !='李白' ; 
+-- 14. 查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩
+select distinct student.student_id,count(student.student_id) over (partition by student.student_id) 不及格课程个数,student.student_name,avg(score) over (partition by student.student_id) from student,score where student.student_id=score.student_id and score.score<60;
+
+-- 15. 检索" 1 "课程分数小于 60，按分数降序排列的学生信息
+SELECT * from student s,score c WHERE s.student_id=c.student_id and c.course_id=1 and score<60 ORDER BY c.score desc;
+-- 16. 按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
+with aa as 
+(SELECT student.student_id,student.student_name,student.birthday,student.gender,score.course_id,score,avg( score ) over (PARTITION BY student.student_id ) 平均成绩 FROM student,score WHERE student.student_id = score.student_id) select * from aa order by 平均成绩 desc;
+;
+-- 17. 查询各科成绩最高分、最低分和平均分
+SELECT DISTINCT c.course_name,MAX(score) over(PARTITION by c.course_id),MIN(score) over(PARTITION by c.course_id),AVG(score) over(PARTITION by c.course_id) from score s,course c WHERE s.course_id=c.course_id ;
+
+-- 18. 以如下形式显示：课程 ID，课程 name，最高分，最低分，平均分，及格率，中等率，优良率，优秀率（及格为>=60，中等为：70-80，优良为：80-90，优秀为：>=90），要求输出课程号和选修人数，查询结果按人数降序排列，若人数相同，按课程号升序排列
+-- 19. 按各科成绩进行排序，并显示排名，Score 重复时保留名次空缺
+SELECT c.course_name,score,RANK() over(PARTITION by c.course_id ORDER BY score desc) from score s,course c where s.course_id=c.course_id;
+-- 20. 按各科成绩进行排序，并显示排名，Score 重复时合并名次
+SELECT c.course_name,score,DENSE_RANK() over(PARTITION by c.course_id ORDER BY score desc) from score s,course c where s.course_id=c.course_id;
+-- 21. 查询学生的总成绩，并进行排名，总分重复时保留名次空缺
+WITH a as 
+(SELECT DISTINCT s.student_id,s.student_name,sum(score) over(PARTITION by s.student_id) 总成绩 from student s,score c WHERE s.student_id=c.student_id)
+SELECT *,RANK() over(ORDER BY 总成绩 desc ) from a;
+-- 22. 查询学生的总成绩，并进行排名，总分重复时不保留名次空缺
+WITH a as 
+(SELECT DISTINCT s.student_id,s.student_name,sum(score) over(PARTITION by s.student_id) 总成绩 from student s,score c WHERE s.student_id=c.student_id)
+SELECT *,DENSE_RANK() over(ORDER BY 总成绩 desc ) from a;
+-- 23. 统计各科成绩各分数段人数：课程编号，课程名称，[100-85]，[85-70]，[70-60]，[60-0] 及所占百分比
+-- 24. 查询各科成绩前三名的记录
+with aa as 
+(SELECT student.student_id,student.student_name,student.birthday,student.gender,score.course_id,score, DENSE_RANK() over (PARTITION BY score.course_id order by score.score desc) 排名 FROM student,score WHERE student.student_id = score.student_id)
+select * from aa where 排名<=3;
+-- 25. 查询每门课程被选修的学生数
+select distinct course.course_id,course_name,count(student.student_id) over (partition by score.course_id) 学生数 from student,score,course where student.student_id=score.student_id and score.course_id=course.course_id;
+-- 26. 查询出只选修两门课程的学生学号和姓名
+WITH a as 
+(SELECT DISTINCT s.student_id,s.student_name,COUNT(c.course_id) over(PARTITION by s.student_id) 课程数量 from student s,course c,score r WHERE s.student_id=r.student_id and c.course_id=r.course_id) 
+SELECT * from a WHERE 课程数量=2;
+-- 27. 查询男生、女生人数
+SELECT DISTINCT gender,COUNT(*) over(PARTITION by gender) from student;
+-- 28. 查询名字中含有「风」字的学生信息
+SELECT * from student where student_name like '%风%';
+-- 29. 查询同名同性学生名单，并统计同名人数
+-- 30. 查询 1990 年出生的学生名单
+SELECT * from student WHERE YEAR(birthday)=1990;
+-- 31. 查询每门课程的平均成绩，结果按平均成绩降序排列，平均成绩相同时，按课程编号升序排列
+WITH a as 
+(SELECT DISTINCT c.course_name,c.course_id,avg(score) over(PARTITION by c.course_id ) 平均成绩 from score s,course c WHERE s.course_id=c.course_id)
+SELECT *,ROW_NUMBER() over(order by 平均成绩  desc),ROW_NUMBER() over(order by a.course_id) FROM a;
+
+-- 32. 查询平均成绩大于等于 85 的所有学生的学号、姓名和平均成绩
+with a as
+(SELECT DISTINCT s.student_id,s.student_name,avg(c.score) over(PARTITION by s.student_id) 平均成绩 from student s, score c WHERE s.student_id=c.student_id) 
+SELECT * FROM a where 平均成绩>85;
+-- 33. 查询课程名称为「数学」，且分数低于 60 的学生姓名和分数
+SELECT c.course_name, s.student_name,r.score from student s,course c,score r WHERE s.student_id=r.student_id and c.course_id=r.course_id and c.course_name='数学' and r.score<60;
+-- 34. 查询所有学生的课程及分数情况（存在学生没成绩，没选课的情况）
+SELECT * from student s left JOIN score r on s.student_id= r.student_id left JOIN course c on c.course_id=r.course_id; 
+-- 35. 查询任何一门课程成绩在 70 分以上的姓名、课程名称和分数
+SELECT s.student_name,c.course_name,r.score from student s,score r,course c WHERE s.student_id=r.student_id and c.course_id=r.course_id and score>70 ORDER BY c.course_id;
+-- 36. 查询不及格的课程
+SELECT DISTINCT c.course_name from student s,course c,score r WHERE s.student_id=r.student_id and c.course_id=r.course_id and score<60;
+-- 37. 查询课程编号为 1 且课程成绩在 80 分以上的学生的学号和姓名
+SELECT s.student_id,s.student_name from student s,score r WHERE s.student_id=r.student_id and course_id=1 and r.score>=80;
+-- 38. 求每门课程的学生人数
+SELECT DISTINCT c.course_name,COUNT(s.student_id) over(PARTITION by c.course_id) from student s, course c,score r WHERE s.student_id=r.student_id and c.course_id=r.course_id;
+-- 39. 成绩不重复，查询选修「Trump」老师所授课程的学生中，成绩最高的学生信息及其成绩
+select * from student,score where student.student_id=score.student_id and score=(
+select max(score) from student,score,course,teacher where student.student_id=score.student_id and score.course_id=course.course_id and course.teacher_id=teacher.teacher_id and teacher_name='Trump');
+-- 40. 成绩有重复的情况下，查询选修「张三」老师所授课程的学生中，成绩最高的学生信息及其成绩
+select * from student,score,course,teacher where student.student_id=score.student_id and score.course_id=course.course_id and course.teacher_id=teacher.teacher_id and score=(
+select max(score) from student,score,course,teacher where student.student_id=score.student_id and score.course_id=course.course_id and course.teacher_id=teacher.teacher_id and teacher_name='李白') and teacher_name='李白';
+-- 41. 查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩
+with bb as 
+(with aa as 
+(select distinct  student.student_id,score.course_id,score,count(student.student_id) over (partition by score ) 课程成绩相同个数 from student,score where student.student_id=score.student_id) 
+select *,count(student_id) over(partition by student_id) 学生编号个数 from aa where 课程成绩相同个数 >=2) 
+select bb.student_id,bb.course_id,bb.score from bb where 学生编号个数>=2;
+
+-- 42. 查询每门功成绩最好的前两名
+with aa as 
+(SELECT student.student_id,student.student_name,student.birthday,student.gender,score.course_id,score, DENSE_RANK() over (PARTITION BY score.course_id order by score.score desc) 排名 FROM student,score WHERE student.student_id = score.student_id)
+select * from aa where 排名<=2;
+-- 43. 统计每门课程的学生选修人数（超过 5 人的课程才统计）。
+with aa as 
+(select distinct  course_id,count(student.student_id) over (partition by course_id) 学生选修人数 from student,score where student.student_id=score.student_id)
+select * from aa where 学生选修人数>5;
+-- 44. 检索至少选修两门课程的学生学号
+WITH a as 
+(SELECT DISTINCT s.student_id,COUNT(c.course_id) over(PARTITION by s.student_id) 课程数量 from student s,course c,score r WHERE s.student_id=r.student_id and c.course_id=r.course_id) 
+SELECT * from a WHERE 课程数量>=2;
+-- 45. 查询选修了全部课程的学生信息
+WITH a as 
+(SELECT DISTINCT s.student_id,s.student_name,s.gender,s.birthday,COUNT(c.course_id) over(PARTITION by s.student_id) 课程数量 from student s,course c,score r WHERE s.student_id=r.student_id and c.course_id=r.course_id) 
+SELECT * from a WHERE 课程数量=3;
+-- 46. 查询各学生的年龄，只按年份来算
+select *,datediff(NOW(),birthday)/365 from student;
+-- 47. 按照出生日期来算，当前月日 < 出生年月的月日则，年龄减一
+
+-- 48. 查询本周过生日的学生
+select week(now(),1)
+select *,week(birthday,1) from student where week(birthday,1)=week(NOW(),1);
+-- 49. 查询下周过生日的学生
+select week(now(),1)
+select *,week(birthday,1) from student where week(birthday,1)=week(NOW(),1)+1;
+-- 50. 查询本月过生日的学生
+select *,MONTH(birthday)  from student where MONTH(birthday) =MONTH(NOW());
+-- 51. 查询下月过生日的学生
+select *,MONTH(birthday)  from student where MONTH(birthday) =MONTH(NOW())+1;
+
+```
+
-- 
Gitee