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Date: Sun, 22 Oct 2023 15:17:10 +0000
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Signed-off-by: 陈正楠 <12461668+kkkjj2222222256@user.noreply.gitee.com>
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+```mysql
+##  题目：
+
+-- 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 * from student,(SELECT s1.student_id,s1.score 第一门课,s2.score 第二门课
+FROM score s1, score s2 WHERE s1.course_id = 1 AND s2.course_id = 2 AND s1.student_id = s2.student_id AND s1.score > s2.score) a where student.student_id = a.student_id;
+
+-- 2. 查询同时参与" 1 "课程和" 2 "课程考试的学生信息
+SELECT * from (
+SELECT * from student  where  student_id in (SELECT student_id from score where course_id =1 or course_id=2 GROUP BY student_id HAVING COUNT(*)>1))a left join score b on 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 )
+
+-- 4. 查询不存在" 1 "课程但存在" 2 "课程的情况
+SELECT * from score where student_id not in (
+SELECT student_id from score where course_id=1);
+-- 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 a.student_id , student_name,AVG(score) from student a JOIN score b on a.student_id= b.student_id GROUP BY a.student_id HAVING AVG(score)>=60;
+
+
+
+-- 6. 查询在成绩表存在成绩的学生信息
+SELECT * FROM score LEFT JOIN student on score.student_id= student.student_id;
+
+-- 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 DISTINCT st.student_id,COUNT(course_id)over(PARTITION by st.student_id),SUM(score) over(PARTITION by st.student_id) from score sc RIGHT JOIN student st on st.student_id=sc.student_id ;
+-- 8. 查询「李」姓老师的数量
+SELECT COUNT(teacher_name) 姓李的数量 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 teacher JOIN course on teacher.teacher_id=course.teacher_id JOIN score on score.course_id=course.course_id 
+JOIN student ON student.student_id=score.student_id
+WHERE teacher_name="李白";
+-- 10. 查询没有学全所有课程的同学的信息
+SELECT * from student  WHERE student_id in
+(SELECT DISTINCT student_id from score where student_id not in
+(SELECT s1.student_id from score s1,score s2,score s3 where s1.student_id=s2.student_id and s2.student_id=s3.student_id and s1.course_id=1 and s2.course_id=2 and s3.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 DISTINCT student_id from score where course_id  in
+(SELECT course_id from score where student_id=1) and 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
+-- 13. 查询没学过「李白」老师讲授的任一门课程的学生姓名
+SELECT * from student where student_id=
+(SELECT DISTINCT student_id from score where student_id not in 
+(SELECT student_id from score where course_id  in
+(SELECT course_id from course where teacher_id =
+(SELECT teacher_id  from teacher WHERE teacher_name='李白')) GROUP BY student_id));
+-- 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
+with a as 
+(SELECT *,avg(score)over(PARTITION by student_id ) av ,COUNT(score)over(PARTITION by student_id ) s  from score where score<60 )
+SELECT DISTINCT st.student_id ,student_name,a.av 平均成绩  from a inner JOIN student st on a.student_id=st.student_id where  a.s>=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 st.*,sc.score from  score sc,student st where sc.student_id=st.student_id and 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
+-- 17. 查询各科成绩最高分、最低分和平均分
+     SELECT course_id, 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
+-- 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 *,rank()  over (PARTITION by course_id ORDER BY score desc)   from score;
+-- 20. 按各科成绩进行排序，并显示排名，Score 重复时合并名次
+SELECT course_id,score,DENSE_RANK() over(PARTITION by course_id ORDER BY score) FROM score;
+
+-- 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 s.student_id,s.student_name, SUM(sc.score) 总成绩,RANK() over(ORDER BY SUM(sc.score) DESC) 排名 from student s JOIN score sc ON s.student_id = sc.student_id GROUP BY sc.student_id;
+
+-- 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 s.student_id,s.student_name, SUM(sc.score) 总成绩,DENSE_RANK() over(ORDER BY SUM(sc.score) DESC) 排名 from student s JOIN score sc ON s.student_id = sc.student_id GROUP BY sc.student_id;
+
+-- 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 * from
+(SELECT *,ROW_NUMBER()over(PARTITION by course_id ORDER BY score DESC) a from score sc )b INNER JOIN student st  on b.student_id=st.student_id WHERE b.a in (1,2,3)
+
+-- 24. 查询各科成绩前三名的记录
+SELECT * from
+(SELECT *,ROW_NUMBER()over(PARTITION by course_id ORDER BY score DESC) a from score sc )b INNER JOIN student st  on b.student_id=st.student_id WHERE b.a in (1,2,3)
+
+-- 25. 查询每门课程被选修的学生数
+SELECT DISTINCT sc.course_id,course_name,COUNT(student_id)over(PARTITION by course_id) 学生数  from score sc INNER JOIN course co ON sc.course_id= co.course_id
+
+-- 26. 查询出只选修两门课程的学生学号和姓名
+SELECT  sc.student_id, student_name, COUNT(sc.course_id) from score sc INNER JOIN student st on sc.student_id=st.student_id GROUP BY sc.student_id HAVING COUNT(sc.course_id)=2
+
+-- 27. 查询男生、女生人数
+SELECT count(*)   from student where gender='男';
+SELECT DISTINCT gender,count(*) 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 where 
+-- 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
+-- 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  avg(score)  平均 from course inner join score on course.course_id=score.course_id JOIN student on score.student_id=student.student_id ;
+-- 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 student_name,score from course inner join score on course.course_id=score.course_id JOIN student on score.student_id=student.student_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 DISTINCT * FROM student s LEFT JOIN score on s.student_id=score.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 * FROM student s1,(
+SELECT student_id,score,course_id FROM score WHERE score>70) a,course c WHERE s1.student_id=a.student_id and c.course_id=a.course_id;
+-- 36. 查询不及格的课程
+SELECT co.course_id,co.course_name,score from course co INNER JOIN score sc on co.course_id=sc.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 sc.course_id,st.student_name,score from  score sc INNER JOIN student st on sc.student_id=st.student_id  where  sc.course_id=1 and score>80;
+
+-- 38. 求每门课程的学生人数
+SELECT DISTINCT course_name,COUNT(course_name) over( PARTITION by course_name  ORDER BY course_name)FROM student JOIN score on student.student_id=score.student_id JOIN course on course.course_id=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 * FROM student s1,score s2 WHERE s1.student_id=s2.student_id and score=(
+SELECT max(score) FROM score WHERE course_id=(
+SELECT DISTINCT course_id FROM course WHERE teacher_id=(
+SELECT teacher_id FROM teacher WHERE teacher_name='张三')));
+-- 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
+-- 42. 查询每门功成绩最好的前两名
+with a as (
+SELECT student_id,course_id,rank() over(PARTITION by course_id ORDER BY score) 排名 FROM score)
+SELECT * FROM a 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）。
+SELECT course_id,count(*) 选修人数 FROM score GROUP BY course_id HAVING 选修人数 >5
+
+-- 44. 检索至少选修两门课程的学生学号
+SELECT student_id,count(course_id) 选修 FROM score GROUP BY student_id HAVING 选修 >=2;
+
+-- 45. 查询选修了全部课程的学生信息
+SELECT * FROM student s,( 
+SELECT student_id,count(course_id) 课程 FROM score GROUP BY student_id HAVING 课程=(SELECT count(*) FROM course)) a WHERE s.student_id=a.student_id;
+-- 46. 查询各学生的年龄，只按年份来算
+SELECT student_name,year(NOW())-year(birthday) 年龄  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 student_id, student_name, birthday
+FROM student
+WHERE WEEK(birthday) = WEEK(CURRENT_DATE());
+
+-- 49. 查询下周过生日的学生
+SELECT student_id, student_name, birthday
+FROM student
+WHERE WEEK(birthday) = WEEK(CURRENT_DATE()) + 1;
+ 
+-- 50. 查询本月过生日的学生
+SELECT student_id, student_name, birthday
+FROM student
+WHERE MONTH(birthday) = MONTH(CURRENT_DATE());
+-- 51. 查询下月过生日的学生
+with a as (
+SELECT student_name,MONTH(birthday) 生日月 FROM student)
+SELECT * FROM a WHERE 生日月=month(NOW()+1);
+```
+
-- 
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