From dc7dd5bd4013b46783fc55a33afee4b86af808f8 Mon Sep 17 00:00:00 2001
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 <11785147+demon-cat-fruit-orange@user.noreply.gitee.com>
Date: Sun, 22 Oct 2023 14:59:37 +0000
Subject: [PATCH] =?UTF-8?q?=E4=BD=9C=E4=B8=9A?=
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Signed-off-by: 施晟宸 <11785147+demon-cat-fruit-orange@user.noreply.gitee.com>
---
 ...\346\215\256\345\272\22350\351\242\230.md" | 307 ++++++++++++++++++
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diff --git "a/22 \346\226\275\346\231\237\345\256\270/20231020\346\225\260\346\215\256\345\272\22350\351\242\230.md" "b/22 \346\226\275\346\231\237\345\256\270/20231020\346\225\260\346\215\256\345\272\22350\351\242\230.md"
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@@ -0,0 +1,307 @@
+```sql
+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
+SELECT 
+DISTINCT
+  b.student_id,
+    b.student_name,
+    b.gender,
+  b.birthday,
+    b.score  
+    from
+(SELECT
+    stu.student_id,
+    stu.student_name,
+    stu.gender,
+    stu.birthday,
+    s.score 
+FROM
+    student stu
+    JOIN score s
+    JOIN course cou ON stu.student_id = s.student_id 
+    AND s.course_id = cou.course_id WHERE s.course_id=1) a
+    JOIN
+    (SELECT
+    stu.student_id,
+    stu.student_name,
+    stu.gender,
+    stu.birthday,
+    s.score 
+FROM
+    student stu
+    JOIN score s
+    JOIN course cou ON stu.student_id = s.student_id 
+    AND s.course_id = cou.course_id WHERE s.course_id=2) 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
+SELECT
+DISTINCT
+  a.student_id,
+    a.student_name,
+    a.birthday,
+    a.gender
+    from
+(SELECT
+  cou.course_id,
+    stu.student_id,
+    stu.student_name,
+    stu.gender,
+    stu.birthday,
+    s.score 
+FROM
+    student stu
+    JOIN score s
+    JOIN course cou ON stu.student_id = s.student_id 
+    AND s.course_id = cou.course_id WHERE cou.course_id=1 or cou.course_id=2) a
+    JOIN
+    (SELECT
+    cou.course_id,
+    stu.student_id,
+    stu.student_name,
+    stu.gender,
+    stu.birthday,
+    s.score 
+
+FROM
+    student stu
+    JOIN score s
+    JOIN course cou ON stu.student_id = s.student_id 
+    AND s.course_id = cou.course_id WHERE cou.course_id=1 or cou.course_id=2) b
+    where a.course_id=1 and b.course_id=2 and 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 )
+		select *
+from (select student_id ,score from score where score.course_id='01')as t1 left join  (select student_id ,score from score where score.course_id='02') as t2
+on t1.student_id=t2.student_id  不会
+-- 4. 查询不存在" 1 "课程但存在" 2 "课程的情况
+select *
+from score
+where score.student_id not in (select student_id from score where score.course_id='01')
+and  score.course_id='02'   不会
+-- 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 student.student_id,student_name,avg(score) FROM student RIGHT JOIN score on student.student_id=score.student_id GROUP BY student.student_id HAVING avg(score)>60
+-- 6. 查询在成绩表存在成绩的学生信息
+SELECT DISTINCT student.* FROM student RIGHT JOIN score on student.student_id=score.student_id WHERE 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 student.student_id,student_name,count(course_id),sum(score) FROM student LEFT JOIN score on student.student_id=score.student_id GROUP BY student.student_id ;
+-- 8. 查询「李」姓老师的数量
+SELECT count(teacher_id) 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 WHERE student_id in(SELECT student_id FROM score WHERE course_id in(SELECT course_id FROM course WHERE teacher_id in(SELECT teacher_id FROM teacher WHERE teacher_name='李白'
+)))
+-- 10. 查询没有学全所有课程的同学的信息
+SELECT student.*,COUNT(course_id) FROM score RIGHT JOIN student on score.student_id=student.student_id GROUP BY student.student_id HAVING COUNT(course_id)<(SELECT count(*) FROM course
+)
+
+
+SELECT * FROM student WHERE student_id not in(SELECT student_id FROM score WHERE course_id=1 and student_id in(SELECT student_id FROM score WHERE course_id=2) and student_id in (SELECT student_id FROM score WHERE course_id=3))
+-- 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 WHERE student_id in(SELECT student_id FROM score WHERE course_id in(SELECT course_id FROM score WHERE 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
+SELECT student_id,course_id FROM score WHERE student_id=1
+SELECT * FROM score WHERE course_id in(SELECT course_id FROM score WHERE student_id=1
+) and course_id=2 and
+-- 13. 查询没学过「李白」老师讲授的任一门课程的学生姓名
+SELECT course_id FROM course WHERE teacher_id in(SELECT teacher_id FROM teacher WHERE teacher_name='李白')
+SELECT student_id FROM score WHERE course_id =(SELECT course_id FROM course WHERE teacher_id in(SELECT teacher_id FROM teacher WHERE teacher_name='李白'))
+
+SELECT student_name FROM student WHERE student_id not in(SELECT student_id FROM score WHERE course_id =(SELECT course_id FROM course WHERE teacher_id in(SELECT teacher_id FROM teacher WHERE 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 student.student_id,student_name,AVG(score) FROM score left JOIN student on score.student_id=student.student_id WHERE score<60 GROUP BY student.student_id HAVING count(*)>=2
+
+
+-- 15. 检索" 1 "课程分数小于 60，按分数降序排列的学生信息
+SELECT student_id FROM score WHERE course_id=1 and score<60 ORDER BY score desc
+SELECT * FROM student WHERE student_id in(SELECT student_id FROM score WHERE course_id=1 and score<60 ORDER BY 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
+SELECT avg(score) FROM student RIGHT JOIN score on student.student_id=score.student_id GROUP BY student.student_id ORDER BY avg(score) desc
+SELECT student_id,AVG(SCORE) FROM score GROUP BY student_id
+-- 17. 查询各科成绩最高分、最低分和平均分
+SELECT max(score),min(score),avg(score) FROM score GROUP BY 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
+select score.course_id ,max(score.score)as 最高分,min(score.score)as 最低分,AVG(score.score)as 平均分,count(*)as 选修人数,sum(case when score.score>=60 then 1 else 0 end )/count(*)as 及格率,sum(case when score.score>=70 and score.score<80 then 1 else 0 end )/count(*)as 中等率,sum(case when score.score>=80 and score.score<90 and score.score<80 then 1 else 0 end )/count(*)as 优良率,sum(case when score.score>=90 then 1 else 0 end )/count(*)as 优秀率 不会
+from score
+GROUP BY score.course_id
+ORDER BY count(*)DESC,score.course_id asc
+-- 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  student_id,course_id,score,DENSE_RANK() over (PARTITION by course_id ORDER BY score desc)from score 不会
+-- 20. 按各科成绩进行排序，并显示排名，Score 重复时合并名次
+select  student_id,course_id,score,DENSE_RANK() over (PARTITION by course_id ORDER BY score desc)from score; 不会
+-- 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
+SELECT student_id, SUM(score) 总成绩,RANK() over(ORDER BY SUM(score) DESC) 排名 from score GROUP BY student_id; 不会
+-- 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
+SELECT student_id, SUM(score) 总成绩,dense_RANK() over(ORDER BY SUM(score) DESC) 排名 from score GROUP BY student_id; 不会
+
+-- 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
+SELECT
+	course.course_id,
+	course.course_name,
+	CASE 
+		WHEN score >= 85 THEN '[100-85]'
+		WHEN score >= 70 THEN '[85-70]'
+		WHEN score >= 60 THEN '[70-60]'
+	ELSE '[60-0]'
+END 
+FROM
+	score,
+	course
+WHERE
+	score.course_id = course.course_id ;不会
+-- 24. 查询各科成绩前三名的记录
+select *
+from score as t1
+where (select count(*) from score as t2 where t1.course_id=t2.course_id and t2.score >t1.score)<3
+ORDER BY t1.course_id
+-- 25. 查询每门课程被选修的学生数
+SELECT course_name,count(student_id) FROM score LEFT JOIN course on score.course_id=course.course_id GROUP BY course_name
+-- 26. 查询出只选修两门课程的学生学号和姓名
+SELECT student.student_id,student.student_name FROM student LEFT JOIN score on student.student_id=score.student_id GROUP BY student.student_id HAVING count(course_id)=2 ;
+-- 27. 查询男生、女生人数
+SELECT gender,count(student_id) FROM student GROUP BY gender
+-- 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
+SELECT * FROM student s1,st
+-- 30. 查询 1990 年出生的学生名单
+SELECT * FROM student WHERE LEFT(birthday,5)=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
+SELECT score.course_id,course_name,avg(score) FROM score LEFT JOIN course on score.course_id=course.course_id GROUP BY score.course_id ORDER BY avg(score) desc,score.course_id asc
+-- 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
+SELECT student.student_id,student_name,avg(score) FROM score LEFT JOIN student on score.student_id=student.student_id GROUP BY student_id HAVING avg(score)>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 course_name,student_name,score FROM score LEFT JOIN student on score.student_id=student.student_id LEFT JOIN course on score.course_id=course.course_id WHERE course_name='数学' and 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 student_name,course_name,score FROM score right JOIN student on score.student_id=student.student_id LEFT JOIN course on score.course_id=course.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 student_name,course_name,score FROM score right JOIN student on score.student_id=student.student_id LEFT JOIN course on score.course_id=course.course_id WHERE score>70
+-- 36. 查询不及格的课程
+SELECT student_name,course_name,score FROM score right JOIN student on score.student_id=student.student_id LEFT JOIN course on score.course_id=course.course_id WHERE 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 student.student_id,student_name FROM score right JOIN student on score.student_id=student.student_id  WHERE course_id=1 and score>80
+-- 38. 求每门课程的学生人数
+SELECT course_name,COUNT(student.student_id) FROM score left JOIN student on score.student_id=student.student_id LEFT JOIN course on score.course_id=course.course_id GROUP BY score.course_id
+-- 39. 成绩不重复，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 student.*,score FROM student left join score on student.student_id=score.student_id LEFT JOIN course on score.course_id=course.course_id LEFT JOIN teacher on course.teacher_id=teacher.teacher_id
+ WHERE teacher_name='李白' LIMIT 1
+-- 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
+
+-- 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
+select *
+from score as t1
+where exists(select * from score as t2 where t1.student_id=t2.student_id and t1.course_id!=t2.course_id and t1.score =t2.score )
+-- 42. 查询每门功成绩最好的前两名
+select *
+from score as t1
+where (select count(*) from score as t2 where t1.course_id=t2.course_id and t2.score >t1.score)<2
+ORDER BY t1.course_id
+-- 43. 统计每门课程的学生选修人数（超过 5 人的课程才统计）。
+SELECT course_id,count(student_id) FROM score GROUP BY course_id HAVING count(student_id)>5
+-- 44. 检索至少选修两门课程的学生学号
+SELECT student_id,count(course_id) FROM score GROUP BY student_id HAVING count(course_id)>=2
+-- 45. 查询选修了全部课程的学生信息
+SELECT count(*) FROM course
+SELECT student.*,COUNT(course_id) FROM score  JOIN student on score.student_id=student.student_id GROUP BY student.student_id HAVING COUNT(course_id)=(SELECT count(*) FROM course
+)
+-- 46. 查询各学生的年龄，只按年份来算
+select student.student_id,student.student_name,YEAR(NOW())-YEAR(birthday) 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
+select student.student_id,student.student_name,TIMESTAMPDIFF(YEAR,student.birthday,CURDATE()) from student;
+-- 48. 查询本周过生日的学生
+SELECT * FROM student WHERE WEEK(birthday) = WEEK(NOW())
+-- 49. 查询下周过生日的学生
+SELECT 
+  *
+FROM
+  student 
+WHERE WEEK(birthday) = WEEK(NOW()) + 1
+-- 50. 查询本月过生日的学生
+SELECT 
+ *
+FROM
+  student 
+WHERE MONTH(birthday) = MONTH(NOW());
+-- 51. 查询下月过生日的学生
+-- 
+SELECT 
+  *
+FROM
+  student 
+WHERE MONTH(birthday) = MONTH(NOW()) + 1 ;
+```
-- 
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