现有用户信息表user_info(uid用户ID,nick_name昵称, achievement成就值, level等级, job职业方向, register_time注册时间),示例数据如下: id uid nick_name achievement level job register_time 1 1001 牛客1号 3100 7 算法 2020-01-01 10:00:00 2 1002 牛客2号 2100 6 算法 2020-01-01 10:00:00 3 1003 牛客3号 1500 5 算法 2020-01-01 10:00:00 4 1004 牛客4号 1100 4 算法 2020-01-01 10:00:00 5 1005 牛客5号 1600 6 C++ 2020-01-01 10:00:00 6 1006 牛客6号 3000 6 C++ 2020-01-01 10:00:00 释义:用户1001昵称为牛客1号,成就值为3100,用户等级是7级,职业方向为算法,注册时间2020-01-01 10:00:00 试卷信息表examination_info(exam_id试卷ID, tag试卷类别, difficulty试卷难度, duration考试时长, release_time发布时间) 示例数据如下: id exam_id tag difficulty duration release_time 1 9001 SQL hard 60 2021-09-01 06:00:00 2 9002 C++ easy 60 2020-02-01 10:00:00 3 9003 算法 medium 80 2020-08-02 10:00:00 试卷作答记录表exam_record(uid用户ID, exam_id试卷ID, start_time开始作答时间, submit_time交卷时间, score得分) 示例数据如下: id uid exam_id start_time submit_time score 1 1001 9001 2021-07-02 09:01:01 2021-09-01 09:41:01 70 2 1002 9003 2021-09-01 12:01:01 2021-09-01 12:21:01 60 3 1002 9002 2021-09-02 12:01:01 2021-09-02 12:31:01 70 4 1002 9001 2021-09-01 19:01:01 2021-09-01 19:40:01 80 5 1002 9003 2021-08-01 12:01:01 2021-08-01 12:21:01 60 6 1002 9002 2021-08-02 12:01:01 2021-08-02 12:31:01 70 7 1002 9001 2021-09-01 19:01:01 2021-09-01 19:40:01 85 8 1002 9002 2021-07-06 12:01:01 (NULL) (NULL) 9 1003 9002 2021-09-07 10:01:01 2021-09-07 10:31:01 86 10 1003 9003 2021-09-08 12:01:01 2021-09-08 12:11:01 40 11 1003 9003 2021-09-01 13:01:01 2021-09-01 13:41:01 70 12 1003 9001 2021-09-08 14:01:01 (NULL) (NULL) 13 1003 9002 2021-09-08 15:01:01 (NULL) (NULL) 14 1005 9001 2021-09-01 12:01:01 2021-09-01 12:31:01 90 15 1005 9002 2021-09-01 12:01:01 2021-09-01 12:31:01 88 16 1005 9002 2021-09-02 12:11:01 2021-09-02 12:31:01 89 请计算每张SQL类别试卷发布后,当天5级以上的用户作答的人数uv和平均分avg_score,按人数降序,相同人数的按平均分升序,示例数据结果输出如下: exam_id uv avg_score 9001 3 81.3 解释:只有一张SQL类别的试卷,试卷ID为9001,发布当天(2021-09-01)有1001、1002、1003、1005作答过,但是1003是5级用户,其他3位为5级以上,他们三的得分有[70,80,85,90],平均分为81.3(保留1位小数)。
示例1

输入

drop table if exists examination_info,user_info,exam_record;
CREATE TABLE examination_info (
    id int PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    exam_id int UNIQUE NOT NULL COMMENT '试卷ID',
    tag varchar(32) COMMENT '类别标签',
    difficulty varchar(8) COMMENT '难度',
    duration int NOT NULL COMMENT '时长',
    release_time datetime COMMENT '发布时间'
)CHARACTER SET utf8 COLLATE utf8_general_ci;

CREATE TABLE user_info (
    id int PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    uid int UNIQUE NOT NULL COMMENT '用户ID',
    `nick_name` varchar(64) COMMENT '昵称',
    achievement int COMMENT '成就值',
    level int COMMENT '用户等级',
    job varchar(32) COMMENT '职业方向',
    register_time datetime COMMENT '注册时间'
)CHARACTER SET utf8 COLLATE utf8_general_ci;

CREATE TABLE exam_record (
    id int PRIMARY KEY AUTO_INCREMENT COMMENT '自增ID',
    uid int NOT NULL COMMENT '用户ID',
    exam_id int NOT NULL COMMENT '试卷ID',
    start_time datetime NOT NULL COMMENT '开始时间',
    submit_time datetime COMMENT '提交时间',
    score tinyint COMMENT '得分'
)CHARACTER SET utf8 COLLATE utf8_general_ci;

INSERT INTO user_info(uid,`nick_name`,achievement,level,job,register_time) VALUES
  (1001, '牛客1号', 3100, 7, '算法', '2020-01-01 10:00:00'),
  (1002, '牛客2号', 2100, 6, '算法', '2020-01-01 10:00:00'),
  (1003, '牛客3号', 1500, 5, '算法', '2020-01-01 10:00:00'),
  (1004, '牛客4号', 1100, 4, '算法', '2020-01-01 10:00:00'),
  (1005, '牛客5号', 1600, 6, 'C++', '2020-01-01 10:00:00'),
  (1006, '牛客6号', 3000, 6, 'C++', '2020-01-01 10:00:00');

INSERT INTO examination_info(exam_id,tag,difficulty,duration,release_time) VALUES
  (9001, 'SQL', 'hard', 60, '2021-09-01 06:00:00'),
  (9002, 'C++', 'easy', 60, '2020-02-01 10:00:00'),
  (9003, '算法', 'medium', 80, '2020-08-02 10:00:00');

INSERT INTO exam_record(uid,exam_id,start_time,submit_time,score) VALUES
(1001, 9001, '2021-09-01 09:01:01', '2021-09-01 09:41:01', 70),
(1002, 9003, '2021-09-01 12:01:01', '2021-09-01 12:21:01', 60),
(1002, 9002, '2021-09-02 12:01:01', '2021-09-02 12:31:01', 70),
(1002, 9001, '2021-09-01 19:01:01', '2021-09-01 19:40:01', 80),
(1002, 9003, '2021-08-01 12:01:01', '2021-08-01 12:21:01', 60),
(1002, 9002, '2021-08-02 12:01:01', '2021-08-02 12:31:01', 70),
(1002, 9001, '2021-09-01 19:01:01', '2021-09-01 19:40:01', 85),
(1002, 9002, '2021-07-06 12:01:01', null, null),
(1003, 9003, '2021-09-07 10:01:01', '2021-09-07 10:31:01', 86),
(1003, 9003, '2021-09-08 12:01:01', '2021-09-08 12:11:01', 40),
(1003, 9001, '2021-09-01 13:01:01', '2021-09-01 13:41:01', 70),
(1003, 9002, '2021-09-08 14:01:01', null, null),
(1003, 9003, '2021-09-08 15:01:01', null, null),
(1005, 9001, '2021-09-01 12:01:01', '2021-09-01 12:31:01', 90),
(1005, 9002, '2021-09-01 12:01:01', '2021-09-01 12:31:01', 88),
(1005, 9002, '2021-09-02 12:11:01', '2021-09-02 12:31:01', 89);

输出

9001|3|81.3

备注:
结果按人数uv降序,相同人数的按平均分升序
加载中...