【牛客】SQL132 每个题目和每份试卷被作答的人数和次数

作者：IT小白 | 2024-03-07 01:05:39

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描述

现有试卷作答记录表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	2021-09-01 09:01:01	2021-09-01 09:41:01	81
2	1002	9002	2021-09-01 12:01:01	2021-09-01 12:31:01	70
3	1002	9001	2021-09-01 19:01:01	2021-09-01 19:40:01	80
4	1002	9002	2021-09-01 12:01:01	2021-09-01 12:31:01	70
5	1004	9001	2021-09-01 19:01:01	2021-09-01 19:40:01	85
6	1002	9002	2021-09-01 12:01:01	(NULL)	(NULL)

题目练习表practice_record（uid用户ID, question_id题目ID, submit_time提交时间, score得分）：

id	uid	question_id	submit_time	score
1	1001	8001	2021-08-02 11:41:01	60
2	1002	8001	2021-09-02 19:30:01	50
3	1002	8001	2021-09-02 19:20:01	70
4	1002	8002	2021-09-02 19:38:01	70
5	1003	8001	2021-08-02 19:38:01	70
6	1003	8001	2021-08-02 19:48:01	90
7	1003	8002	2021-08-01 19:38:01	80

请统计每个题目和每份试卷被作答的人数和次数，分别按照"试卷"和"题目"的uv & pv降序显示，示例数据结果输出如下：

tid	uv	pv
9001	3	3
9002	1	3
8001	3	5
8002	2	2

解释：“试卷”有3人共练习3次试卷9001，1人作答3次9002；“刷题”有3人刷5次8001，有2人刷2次8002


#在union之前单独排序，需要对表重新命名
select * from
(select
exam_id as tid,count(distinct uid) as uv,count(start_time) as pv
from
exam_record
group by exam_id
order by pv desc,uv desc)t1
 
union
 
select * from
(select
question_id as tid,count(distinct uid) as uv,count(submit_time) as pv
from
practice_record
where submit_time is not null
group by question_id
order by pv desc,uv desc)t2

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