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）： id uid nick_name achievement level job register_time 1 1001 牛客1 1900 2 算法 2020-01-01 10:00:00 2 1002 牛客2号 1200 3 算法 2020-01-01 10:00:00 3 1003 牛客3号♂ 2200 5 算法 2020-01-01 10:00:00 4 1004 牛客4号 2500 6 算法 2020-01-01 10:00:00 5 1005 牛客555号 2000 7 C++ 2020-01-01 10:00:00 6 1006 666666 3000 6 C++ 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）： id exam_id tag difficulty duration release_time 1 9001 C++ hard 60 2020-01-01 10:00:00 2 9002 c# hard 80 2020-01-01 10:00:00 3 9003 SQL medium 70 2020-01-01 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）： id uid exam_id start_time submit_time score 1 1001 9001 2020-01-02 09:01:01 2020-01-02 09:21:59 80 2 1001 9001 2021-05-02 10:01:01 (NULL) (NULL) 4 1001 9001 2021-06-02 19:01:01 2021-06-02 19:32:00 20 3 1001 9002 2021-02-02 19:01:01 2021-02-02 19:30:01 87 5 1001 9002 2021-09-05 19:01:01 2021-09-05 19:40:01 89 6 1001 9002 2021-09-01 12:01:01 (NULL) (NULL) 11 1002 9001 2020-01-01 12:01:01 2020-01-01 12:31:01 81 16 1002 9001 2021-09-06 12:01:01 2021-09-06 12:21:01 80 17 1002 9001 2021-09-06 12:01:01 (NULL) (NULL) 18 1002 9001 2021-09-07 12:01:01 (NULL) (NULL) 7 1002 9002 2021-05-05 18:01:01 2021-05-05 18:59:02 90 12 1002 9002 2020-02-01 12:01:01 2020-02-01 12:31:01 82 13 1002 9002 2020-02-02 12:11:01 2020-02-02 12:31:01 83 9 1003 9001 2021-09-07 10:01:01 2021-09-07 10:31:01 89 8 1003 9003 2021-02-06 12:01:01 (NULL) (NULL) 10 1004 9002 2021-08-06 12:01:01 (NULL) (NULL) 14 1005 9001 2021-02-01 11:01:01 2021-02-01 11:31:01 84 15 1006 9001 2021-02-01 11:01:01 2021-09-01 11:31:01 84 找到昵称以"牛客"+纯数字+"号"或者纯数字组成的用户对于字母c开头的试卷类别（如C,C++,c#等）的已完成的试卷ID和平均得分，按用户ID、平均分升序排序。由示例数据结果输出如下： uid exam_id avg_score 1002 9001 81 1002 9002 85 1005 9001 84 1006 9001 84 解释：昵称满足条件的用户有1002、1004、1005、1006； c开头的试卷有9001、9002； 满足上述条件的作答记录中，1002完成9001的得分有81、80，平均分为81（80.5取整四舍五入得81）； 1002完成9002的得分有90、82、83，平均分为85；
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', 1900, 2, '算法', '2020-01-01 10:00:00'),
  (1002, '牛客2号', 1200, 3, '算法', '2020-01-01 10:00:00'),
  (1003, '牛客3号♂', 2200, 5, '算法', '2020-01-01 10:00:00'),
  (1004, '牛客4号', 2500, 6, '算法', '2020-01-01 10:00:00'),
  (1005, '牛客555号', 2000, 7, 'C++', '2020-01-01 10:00:00'),
  (1006, '666666', 3000, 6, 'C++', '2020-01-01 10:00:00');

INSERT INTO examination_info(exam_id,tag,difficulty,duration,release_time) VALUES
  (9001, 'C++', 'hard', 60, '2020-01-01 10:00:00'),
  (9002, 'c#', 'hard', 80, '2020-01-01 10:00:00'),
  (9003, 'SQL', 'medium', 70, '2020-01-01 10:00:00');
	
INSERT INTO exam_record(uid,exam_id,start_time,submit_time,score) VALUES
(1001, 9001, '2020-01-02 09:01:01', '2020-01-02 09:21:59', 80),
(1001, 9001, '2021-05-02 10:01:01', null, null),
(1001, 9002, '2021-02-02 19:01:01', '2021-02-02 19:30:01', 87),
(1001, 9001, '2021-06-02 19:01:01', '2021-06-02 19:32:00', 20),
(1001, 9002, '2021-09-05 19:01:01', '2021-09-05 19:40:01', 89),
(1001, 9002, '2021-09-01 12:01:01', null, null),
(1002, 9002, '2021-05-05 18:01:01', '2021-05-05 18:59:02', 90),
(1003, 9003, '2021-02-06 12:01:01', null, null),
(1003, 9001, '2021-09-07 10:01:01', '2021-09-07 10:31:01', 89),
(1004, 9002, '2021-08-06 12:01:01', null, null),
(1002, 9001, '2020-01-01 12:01:01', '2020-01-01 12:31:01', 81),
(1002, 9002, '2020-02-01 12:01:01', '2020-02-01 12:31:01', 82),
(1002, 9002, '2020-02-02 12:11:01', '2020-02-02 12:31:01', 83),
(1005, 9001, '2021-02-01 11:01:01', '2021-02-01 11:31:01', 84),
(1006, 9001, '2021-09-01 11:01:01', '2021-09-01 11:31:01', 84),
(1002, 9001, '2021-09-06 12:01:01', '2021-09-06 12:21:01', 80),
(1002, 9001, '2021-09-06 12:01:01', null, null),
(1002, 9001, '2021-09-07 12:01:01', null, null);

输出

1002|9001|81
1002|9002|85
1005|9001|84
1006|9001|84
加载中...