SQL题目50道持续更新

落日映苍穹つ 2022-03-17 05:44 209阅读 0赞

数据如下,我在答题过程中使用的是mysql数据库

create table Student
    (
      S     varchar(10),
      Sname nvarchar(10),
      Sage  datetime,
      Ssex  nvarchar(10)
    );
    insert into Student
    values ('01', N'赵雷', '1990-01-01', N'男');
    insert into Student
    values ('02', N'钱电', '1990-12-21', N'男');
    insert into Student
    values ('03', N'孙风', '1990-05-20', N'男');
    insert into Student
    values ('04', N'李云', '1990-08-06', N'男');
    insert into Student
    values ('05', N'周梅', '1991-12-01', N'女');
    insert into Student
    values ('06', N'吴兰', '1992-03-01', N'女');
    insert into Student
    values ('07', N'郑竹', '1989-07-01', N'女');
    insert into Student
    values ('08', N'王菊', '1990-01-20', N'女');
    
    
    
    create table Course
    (
      C     varchar(10),
      Cname nvarchar(10),
      T     varchar(10)
    );
    insert into Course
    values ('01', N'语文', '02');
    insert into Course
    values ('02', N'数学', '01');
    insert into Course
    values ('03', N'英语', '03');
    
    
    create table Teacher
    (
      T     varchar(10),
      Tname nvarchar(10)
    );
    insert into Teacher
    values ('01', N'张三');
    insert into Teacher
    values ('02', N'李四');
    insert into Teacher
    values ('03', N'王五');
    
    
    create table SC
    (
      S     varchar(10),
      C     varchar(10),
      score decimal(18, 1)
    );
    insert into SC
    values ('01', '01', 80);
    insert into SC
    values ('01', '02', 90);
    insert into SC
    values ('01', '03', 99);
    insert into SC
    values ('02', '01', 70);
    insert into SC
    values ('02', '02', 60);
    insert into SC
    values ('02', '03', 80);
    insert into SC
    values ('03', '01', 80);
    insert into SC
    values ('03', '02', 80);
    insert into SC
    values ('03', '03', 80);
    insert into SC
    values ('04', '01', 50);
    insert into SC
    values ('04', '02', 30);
    insert into SC
    values ('04', '03', 20);
    insert into SC
    values ('05', '01', 76);
    insert into SC
    values ('05', '02', 87);
    insert into SC
    values ('06', '01', 31);
    insert into SC
    values ('06', '03', 34);
    insert into SC
    values ('07', '02', 89);
    insert into SC
    values ('07', '03', 98);
    
    insert into SC
    values ('07', '04', 98);

有些题目可能会有不对的sql,是在写题目的时候打得

# 1. 查询" 01 "课程比" 02 "课程成绩高的学生的信息及课程分数
    
    SELECT Student.S,Sname,Sage, Ssex,C,score_01,score_02
    FROM Student
           JOIN (
      SELECT *
      FROM (SELECT S,C,score score_01 FROM SC WHERE C = '01') a
             LEFT JOIN (SELECT S new_s, C new_c, score score_02 FROM SC WHERE C = '02') b ON a.S = b.new_s
      WHERE a.score_01 > b.score_02) c ON Student.S = c.new_s;
    
    
    # 1.1 查询同时存在" 01 "课程和" 02 "课程的情况
    
    SELECT *
    FROM (SELECT * FROM SC WHERE C = '01') a
           JOIN (SELECT * FROM SC WHERE C = '02') b ON a.S = b.S;
    
    
    # 1.2 查询存在" 01 "课程但可能不存在" 02 "课程的情况(不存在时显示为 null )
    
    SELECT *
    FROM (SELECT * FROM SC WHERE C = '01') a
           LEFT JOIN (SELECT * FROM SC WHERE C = '02') b ON a.S = b.S;
    
    
    # 1.3 查询选课不存在" 01 "课程但存在" 02 "课程的情况
    
    # 解法1
    SELECT *
    FROM SC
    WHERE C = '02'
      AND S NOT IN (SELECT S
                    FROM SC
                    WHERE C = '01');
    
    # 解法2
    SELECT *
    FROM SC A
    WHERE A.C = '02'
      AND NOT EXISTS
      (SELECT S
       FROM SC B
       WHERE A.S = B.S
         AND C = '01');
    
    
    # 解法3
    SELECT *
    FROM (SELECT * FROM SC WHERE C = '01') a
           LEFT JOIN (SELECT * FROM SC WHERE C = '02') b ON a.S = b.S;
    
    
    # 2. 查询平均成绩大于等于 60 分的同学的学生编号和学生姓名和平均成绩
    
    SELECT A.S,B.Sname,A.dc
    FROM (SELECT S,AVG(score) dc FROM SC GROUP BY S HAVING AVG(score) > 60) A
           LEFT JOIN Student B ON A.S = B.S;
    
    
    # 3. 查询在 SC 表存在成绩的学生信息
    
    SELECT *
    FROM Student
    WHERE EXISTS(SELECT * FROM SC where SC.S = Student.S);
    
    
    # 4. 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.S, Student.Sname, 选课总数, 总成绩
    FROM (SELECT S, count(C) 选课总数, sum(score) 总成绩 FROM SC GROUP BY S) A
           RIGHT JOIN Student ON Student.S = A.S;
    
    
    # 4.1 查有成绩的学生信息
    
    SELECT Student.S, Student.Sname, 选课总数, 总成绩
    FROM (SELECT S, count(C) 选课总数, sum(score) 总成绩 FROM SC GROUP BY S) A
           LEFT JOIN Student ON Student.S = A.S;
    
    
    # 5. 查询「李」姓老师的数量 
    
    SELECT COUNT(*)
    FROM Teacher
    where Tname LIKE '李%';
    
    
    # 6. 查询学过「张三」老师授课的同学的信息 
    
    SELECT *
    FROM Student
    WHERE EXISTS(SELECT *
                 FROM SC
                 WHERE Student.S = SC.S
                   AND EXISTS(SELECT *
                              FROM Course
                              WHERE SC.C = Course.C
                                AND EXISTS(SELECT *
                                           FROM Teacher
                                           WHERE Teacher.Tname = '张三'
                                             AND Course.T = Teacher.T)
                   ));
    
    # 7. 查询没有学全所有课程的同学的信息 
    
    # 解法1
    SELECT *
    FROM Student
    WHERE S NOT IN (SELECT S FROM SC GROUP BY S HAVING COUNT(C) = (SELECT COUNT(*) FROM Course));
    
    # 解法2
    SELECT *
    FROM Student
    WHERE NOT EXISTS(
        SELECT S
        FROM SC
        WHERE SC.S = Student.S
        GROUP BY SC.S
        HAVING COUNT(*) = (SELECT COUNT(*) FROM Course)
      );
    
    
    # 8. 查询至少有一门课与学号为" 01 "的同学所学相同的同学的信息 
    
    # 解法1
    SELECT *
    FROM Student
    WHERE S IN (SELECT S
                FROM SC
                WHERE C IN (
                  SELECT DISTINCT C
                  FROM SC
                  WHERE S = '01'
                ));
    
    # 解法2
    SELECT *
    FROM Student
    WHERE EXISTS(
              SELECT *
              FROM SC A
              WHERE A.S = Student.S
                AND EXISTS(
                  SELECT *
                  FROM SC B
                  WHERE A.C = B.C
                    AND B.S = '01'
                ));
    
    
    # 9. 查询和" 01 "号的同学学习的课程完全相同的其他同学的信息 
    
    # 解法1 先把找出选修了其他课程的人, 将其过滤, 然后分组统计
    
    
    SELECT *
    FROM Student C
    WHERE EXISTS(
              SELECT A.S
              FROM SC A
              WHERE C.S = A.S
                AND EXISTS(SELECT * FROM SC B WHERE A.C = B.C AND B.S = '01')
              GROUP BY A.S
              HAVING COUNT(*) = (SELECT COUNT(*) FROM SC WHERE S = '01'));
    
    
    SELECT *
    FROM Student a
    WHERE NOT EXISTS
      (SELECT *
       FROM SC b
       WHERE S = '01'
         AND NOT EXISTS
         (SELECT * FROM SC c WHERE c.S = a.S AND c.C = b.C));
    
    
    # 解法2
    SELECT *
    FROM Student
    WHERE EXISTS(SELECT A.S
                 FROM SC A
                        JOIN (SELECT C FROM SC WHERE S = '01') B ON A.C = B.C
                 WHERE Student.S = A.S
                 GROUP BY A.S
                 HAVING COUNT(*) = (SELECT COUNT(*) FROM SC WHERE S = '01'));
    
    
    # 10. 查询没学过"张三"老师讲授的任一门课程的学生姓名 
    
    SELECT Sname
    FROM Student s
    WHERE NOT EXISTS(
        SELECT *
        FROM SC sc
        WHERE s.S = sc.S
          AND EXISTS(
            SELECT *
            FROM Course c
            WHERE sc.C = c.C
              AND EXISTS(
                SELECT *
                FROM Teacher t
                WHERE c.T = t.T
                  AND t.Tname = '张三'
              )));
    
    
    # 11. 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 *
    FROM Student
    WHERE EXISTS(SELECT S
                 FROM SC
                 WHERE Student.S = SC.S
                 GROUP BY S
                 HAVING SUM(CASE WHEN score < 60 THEN 1 ELSE 0 END) >= 2);
    
    SELECT Student.S,Student.Sname,avg
    FROM Student
           JOIN (SELECT S,avg(score) avg
                 FROM SC
                 GROUP BY S
                 HAVING SUM(CASE WHEN score < 60 THEN 1 ELSE 0 END) >= 2) B ON Student.S = B.S;
    
    
    # 12. 检索" 01 "课程分数小于 60学生信息，按分数降序排列的学生信息
    
    SELECT *
    FROM Student
           JOIN (SELECT *
                 FROM SC
                 WHERE SC.score < 60
    ) B ON Student.S = B.S
    ORDER BY score DESC;
    
    
    # 13. 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 S,
           MAX(CASE C WHEN '01' THEN score ELSE 0 END) '01',
           MAX(CASE C WHEN '02' THEN score ELSE 0 END) '02',
           MAX(CASE C WHEN '03' THEN score ELSE 0 END) '03',
           AVG(score)                                  平均分
    FROM SC
    GROUP BY S
    ORDER BY 平均分 DESC;
    
    # 14. 查询各科成绩最高分、最低分和平均分：
    #     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 ID,
           Cname,
           选修人数,
           最高分,
           最低分,
           平均分,
           及格率,
           中等率,
           优良率,
           优秀率
    FROM Course
           JOIN (SELECT C                                                                            ID,
                        COUNT(*)                                                                     选修人数,
                        MAX(score)                                                                   最高分,
                        MIN(score)                                                                   最低分,
                        AVG(score)                                                                   平均分,
                        SUM(CASE WHEN score >= 60 THEN 1 ELSE 0 END) / COUNT(*) * 100                及格率,
                        SUM(CASE WHEN score >= 70 AND score < 80 THEN 1 ELSE 0 END) / COUNT(*) * 100 中等率,
                        SUM(CASE WHEN score >= 80 AND score < 90 THEN 1 ELSE 0 END) / COUNT(*) * 100 优良率,
                        SUM(CASE WHEN score >= 90 THEN 1 ELSE 0 END) / COUNT(*) * 100                优秀率
                 FROM SC
                 GROUP BY C) A ON Course.C = A.ID
    ORDER BY 选修人数 DESC,ID ASC;
    
    # 15. 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 score,
           CASE
             WHEN @prevRank = score THEN ''
             WHEN @prevRank := score THEN @curRank := @curRank + 1
             END AS 排名
    FROM SC,
         (SELECT @curRank := 0,@prevRank := null) B
    ORDER BY score DESC;
    
    
    # 15.1 按各科成绩进行排序，并显示排名， Score 重复时合并名次
    
    SELECT score,
           CASE
             WHEN @prevRank = score THEN @curRank
             WHEN @prevRank := score THEN @curRank := @curRank + 1
             END AS 排名
    FROM SC,
         (SELECT @curRank := 0,@prevRank := null) B
    ORDER BY score DESC;
    
    
    # 16.  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,
           sum,
           CASE
             WHEN @prevRank = sum THEN ''
             WHEN @prevRanK := sum Then @curRank := @curRank + 1
             END AS PM
    FROM (SELECT S,SUM(score) sum
          FROM SC
          GROUP BY S) A,
         (SELECT @prevRank := NULL,@curRank := 0) B
    ORDER BY sum DESC;
    
    
    # 16.1 查询学生的总成绩，并进行排名，总分重复时不保留名次空
    
    SELECT S,
           sum,
           CASE
             WHEN @prevRank = sum THEN @curRank
             WHEN @prevRanK := sum THEN @curRank := @curRank + 1
             END AS PM
    FROM (SELECT S,SUM(score) sum
          FROM SC
          GROUP BY S) A,
         (SELECT @prevRank := NULL,@curRank := 0) B
    ORDER BY sum DESC;
    
    
    # 17. 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
    
    SELECT *
    FROM Course
           JOIN
         (SELECT C                                                                             课程编号,
                 SUM(CASE WHEN score < 100 AND score >= 85 THEN 1 ELSE 0 END)                  '[100-85]人数',
                 SUM(CASE WHEN score >= 70 THEN 1 ELSE 0 END)                                  '[85-70]人数',
                 SUM(CASE WHEN score >= 60 THEN 1 ELSE 0 END)                                  '[70-60]人数',
                 SUM(CASE WHEN score THEN 1 ELSE 0 END)                                        '[60-0]人数',
                 SUM(CASE WHEN score < 100 AND score >= 85 THEN 1 ELSE 0 END) / COUNT(*) * 100 '[100-85]百分比',
                 SUM(CASE WHEN score >= 70 THEN 1 ELSE 0 END) / COUNT(*) * 100                 '[85-70]百分比',
                 SUM(CASE WHEN score >= 60 THEN 1 ELSE 0 END) / COUNT(*) * 100                 '[70-60]百分比',
                 SUM(CASE WHEN score THEN 1 ELSE 0 END) / COUNT(*) * 100                       '[60-0]百分比'
          FROM SC
          GROUP BY C) b ON Course.C = b.课程编号;
    
    
    # 18. 查询各科成绩前三名的记录
    
    SELECT a.S,a.C,a.score
    FROM SC a
           LEFT JOIN SC b ON a.C = b.C AND a.score < b.score
    GROUP BY a.S,a.C,a.score
    HAVING COUNT(b.S) < 3
    ORDER BY a.C,a.score DESC;
    
    SELECT *
    FROM SC a
    WHERE (SELECT COUNT(DISTINCT score) FROM SC WHERE C = a.C AND score >= a.score) <= 3
    ORDER BY a.C,a.score DESC;
    
    # 19. 查询每门课程被选修的学生数 
    
    SELECT c, COUNT(*)
    FROM SC
    GROUP BY SC.C;
    
    
    # 20. 查询出只选修两门课程的学生学号和姓名 
    
    SELECT Student.Sname,Student.S
    FROM Student
    WHERE (SELECT COUNT(*)
           FROM SC
           WHERE Student.S = SC.S
           GROUP BY SC.S) = 2;
    
    
    # 21. 查询男生、女生人数
    
    SELECT Ssex,COUNT(*)
    FROM Student
    GROUP BY Ssex;
    
    
    # 22. 查询名字中含有「风」字的学生信息
    
    SELECT *
    FROM Student
    WHERE Sname LIKE '%风%';
    
    
    # 23. 查询同名同性学生名单，并统计同名人数
    
    SELECT Sname,Ssex,COUNT(*) 同名人数
    FROM Student
    GROUP BY Student.Sname,Ssex
    HAVING COUNT(*) > 1;
    
    
    # 24. 查询 1990 年出生的学生名单
    
    SELECT *
    FROM Student
    WHERE YEAR(Sage) > 1990;
    
    
    # 25. 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 C, AVG(SC.score) AVG
    FROM SC
    GROUP BY SC.C
    ORDER BY AVG DESC,C ASC;
    
    
    # 26. 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.*,B.AVG
    FROM Student
           JOIN (SELECT S,AVG(score) AVG
                 FROM SC
                 GROUP BY SC.S
                 HAVING AVG >= 85) B ON Student.S = B.S;
    
    
    # 27. 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.*,B.score
    FROM Student
           JOIN (SELECT *
                 FROM SC
                 WHERE EXISTS(SELECT *
                              FROM Course
                              WHERE SC.C = Course.C
                                AND Cname = '数学')
                   AND score < 60) B ON Student.S = B.S;
    
    
    # 28. 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
           LEFT JOIN SC ON Student.S = SC.S;
    
    
    # 29. 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.Sname,Course.Cname,B.score
    FROM Student
           JOIN (SELECT *
                 FROM SC
                 WHERE SC.score > 70) B ON Student.S = B.S
           JOIN Course ON B.C = Course.C;
    
    
    # 30. 查询不及格的课程
    
    SELECT *
    FROM Course
    WHERE EXISTS(SELECT *
                 FROM SC
                 WHERE Course.C = SC.C
                   AND score < 60);
    
    
    # 31. 查询课程编号为 01 且课程成绩在 80 分以上的学生的学号和姓名
    
    SELECT *
    FROM Student
    WHERE EXISTS(SELECT *
                 FROM SC
                 WHERE Student.S = SC.S
                   AND C = '01'
                   AND score = 80);
    
    
    # 32. 求每门课程的学生人数 
    
    SELECT C,COUNT(*)
    FROM SC
    GROUP BY C;
    
    
    # 33. 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.*, B.score
    FROM Student
           JOIN (SELECT *
                 FROM SC
                 WHERE EXISTS(
                           SELECT *
                           FROM Course
                           WHERE SC.C = Course.C
                             AND EXISTS(SELECT *
                                        FROM Teacher
                                        WHERE Course.T = Teacher.T
                                          AND Tname = '张三')
                         )
                 ORDER BY score DESC
                 LIMIT 1) B ON Student.S = B.S;
    
    
    # 34. 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 SC a
    WHERE EXISTS(
        SELECT *
        FROM Course
        WHERE a.C = Course.C
          AND EXISTS(SELECT *
                     FROM Teacher
                     WHERE Course.T = Teacher.T
                       AND Tname = '李四')
      )
      AND (SELECT COUNT(DISTINCT score) FROM SC WHERE C = a.C AND score > a.score) < 1
    ORDER BY a.C,a.score DESC;
    
    
    # 35. 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 SC A
       , SC B
    WHERE A.score = B.score
      AND A.C != B.C
      AND A.S != B.S;
    
    
    # 36. 查询每门功成绩最好的前两名
    
    SELECT *
    FROM SC A
    WHERE (SELECT COUNT(DISTINCT B.score)
           FROM SC B
           WHERE A.C = B.C
             AND B.score > A.score) < 2;
    
    
    # 37. 统计每门课程的学生选修人数（超过 5 人的课程才统计）。
    
    SELECT C
    FROM SC
    GROUP BY C
    HAVING COUNT(*) > 5;
    
    
    # 38. 检索至少选修两门课程的学生学号 
    
    SELECT S
    FROM SC
    GROUP BY S
    HAVING COUNT(*) >= 2;
    
    
    # 39. 查询选修了全部课程的学生信息
    
    SELECT *
    FROM Student
    WHERE EXISTS(SELECT S
                 FROM SC
                 WHERE SC.S = Student.S
                 GROUP BY S
                 HAVING COUNT(*) = (SELECT COUNT(*) FROM Course));
    
    SELECT *
    FROM Student a
    WHERE NOT EXISTS
      (SELECT *
       FROM SC b
       WHERE S = '01'
         AND NOT EXISTS
         (SELECT * FROM SC c WHERE c.S = a.S AND c.C = b.C));
    
    
    # 40. 查询各学生的年龄，只按年份来算 
    
    SELECT (YEAR(NOW()) - YEAR(Sage)) AGE
    FROM Student;
    
    # 41. 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 if(DAY(NOW()) > DAY(Sage) AND MONTH(NOW()) > MONTH(Sage), (YEAR(NOW()) - YEAR(Sage)) - 1,
              (YEAR(NOW()) - YEAR(Sage)))
    FROM Student,
         (SELECT @AGE := 0) B;
    
    
    # 42. 查询本周过生日的学生
    
    SELECT Student.*
    FROM Student
    WHERE WEEK(Sage) = WEEK(NOW());
    
    
    # 43. 查询下周过生日的学生
    
    SELECT Student.*
    FROM Student
    WHERE WEEK(Sage) = WEEK(NOW()) + 1;
    
    
    # 44. 查询本月过生日的学生
    
    SELECT *
    FROM Student
    WHERE MONTH(Student.Sage) = MONTH(NOW());
    
    
    # 45. 查询下月过生日的学生
    
    SELECT *
    FROM Student
    WHERE MONTH(Student.Sage) = MONTH(NOW()) + 1;