sql – 查询滚动日期范围内不同值的计数

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我有一组电子邮件地址和日期,这些电子邮件地址已添加到表格中.各种不同日期的电子邮件地址可以有多个条目.例如,如果我有下面的数据集.我希望得到我们在所述日期和3天前之间的不同电子邮件的日期和数量.
Date   | email  
-------+----------------
1/1/12 | test@test.com
1/1/12 | test1@test.com
1/1/12 | test2@test.com
1/2/12 | test1@test.com
1/2/12 | test2@test.com
1/3/12 | test@test.com
1/4/12 | test@test.com
1/5/12 | test@test.com
1/5/12 | test@test.com
1/6/12 | test@test.com
1/6/12 | test@test.com
1/6/12 | test1@test.com

如果我们使用3的日期,结果集看起来像这样

date   | count(distinct email)
-------+------
1/1/12 | 3
1/2/12 | 3
1/3/12 | 3
1/4/12 | 3
1/5/12 | 2
1/6/12 | 2

我可以使用下面的查询获得日期范围的明确计数,但是希望按天计算范围,这样我就不必手动更新数百个日期的范围.

select test.date,count(distinct test.email)  
from test_table as test  
where test.date between '2012-01-01' and '2012-05-08'  
group by test.date;

感谢帮助.

解决方法

测试用例:
CREATE TEMP TABLE tbl (day date,email text);
INSERT INTO tbl VALUES
 ('2012-01-01','test@test.com'),('2012-01-01','test1@test.com'),'test2@test.com'),('2012-01-02',('2012-01-03',('2012-01-04',('2012-01-05',('2012-01-06','test1@test.com`');

查询 – 仅返回tbl中存在条目的天数:

SELECT day,(SELECT count(DISTINCT email)
       FROM   tbl
       WHERE  day BETWEEN t.day - 2 AND t.day -- period of 3 days
      ) AS dist_emails
FROM   tbl t
WHERE  day BETWEEN '2012-01-01' AND '2012-01-06'  
GROUP  BY 1
ORDER  BY 1;

或者 – 返回指定范围内的所有日期,即使当天没有行:

SELECT day,(SELECT count(DISTINCT email)
       FROM   tbl
       WHERE  day BETWEEN g.day - 2 AND g.day
      ) AS dist_emails
FROM  (SELECT generate_series('2012-01-01'::date,'2012-01-06'::date,'1d')::date) AS g(day)

结果:

day        | dist_emails
-----------+------------
2012-01-01 | 3
2012-01-02 | 3
2012-01-03 | 3
2012-01-04 | 3
2012-01-05 | 1
2012-01-06 | 2

这听起来像window functions的工作,但我没有找到一种方法来定义合适的窗框.另外,per documentation

Aggregate window functions,unlike normal aggregate functions,do not
allow DISTINCT or ORDER BY to be used within the function argument list.

所以我用相关的子查询解决了它.我猜这是最聪明的方式.

我将您的日期列重命名为day,因为使用类型名称作为标识符是不好的做法.

顺便说一下,“在所述日期和3天前之间”将是4天的时间段.你的定义在那里是矛盾的.

有点短,但只有几天慢:

SELECT day,count(DISTINCT email) AS dist_emails
FROM  (SELECT generate_series('2013-01-01'::date,'2013-01-06'::date,'1d')::date) AS g(day)
LEFT   JOIN tbl t ON t.day BETWEEN g.day - 2 AND g.day
GROUP  BY 1
ORDER  BY 1;
原文链接:https://www.f2er.com/mssql/83638.html

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