获取上周的创建和删除条目 [英] Get created as well as deleted entries of last week

问题描述

通过此查询，我可以获取上周创建的所有条目：

With this query I can get all entries created during the last week:

SELECT day, COALESCE(ct, 0) AS ct
FROM  (SELECT now::date - d AS day FROM generate_series (0, 6) d) d  -- 6, not 7
  LEFT   JOIN (
     SELECT created_at::date AS day, count(*) AS ct 
     FROM   entries
     WHERE  created_at >= date_trunc('day', now()) - interval '6d'
     GROUP  BY 1
  ) e USING (day);

它返回这样的结果：

 count | date
   2   |  15.01.2014
   0   |  14.01.2014
   1   |  13.01.2014
   0   |  12.01.2014
   0   |  11.01.2014
   0   |  10.01.2014
   9   |  09.01.2014

现在我还想显示上周所有已删除的条目！我可以通过字段 deleted_at 来获取它们：我尝试过的是：

Now I also want to display all the deleted Entries of last Week! I can get them through the field deleted_at: What I tried was:

SELECT day, COALESCE(ct, 0) AS created, COALESCE(dl,0) AS deleted
FROM  (SELECT current_date - d AS day FROM generate_series (0, 6) d) d  
LEFT   JOIN (
   SELECT created_at::date AS day, 
      count(
        CASE WHEN (created_at >= date_trunc('day', now()) - interval '6d') THEN 1 ELSE 0 END
      ) AS ct,
count(
    CASE WHEN (canceled_at >= date_trunc('day', now()) - interval '6d') THEN 1 ELSE 0 END
) AS dl  
  FROM   entries

   GROUP  BY 1
  ) e USING (day);

但这没用！现在，我得到两个相同的行：

But that didn't work! Now I get two rows that are the same:

deleted | created | date
  2     |  2      |  15.01.2014
  0     |  0      |  14.01.2014
  1     |  1      |  13.01.2014
  0     |  0      |  12.01.2014
  0     |  0      |  11.01.2014
  0     |  0      |  10.01.2014
  9     |  9      |  09.01.2014

我怎么了？我该如何显示已创建和已删除的条目？

What do I wrong? How can I display created as well as deleted entries?

推荐答案

由于两个时间戳在时间范围内都可以存在0-n次，因此彼此独立，您需要做的更多：

Since both timestamps can exist 0 - n times in the time frame and independent from each other, you have to do more:

需要Postgres 9.3 + ：

Requires Postgres 9.3+:

WITH var(ts_min) AS (SELECT date_trunc('day', now()) - interval '6 days')
SELECT day
     , COALESCE(c.created, 0) AS created
     , COALESCE(d.deleted, 0) AS deleted
FROM   var v
CROSS  JOIN LATERAL (
   SELECT d::date AS day
   FROM   generate_series (v.ts_min
                         , v.ts_min + interval '6 days'
                         , interval '1 day') d
   ) t
LEFT   JOIN (
   SELECT created_at::date AS day, count(*) AS created
   FROM   entries
   WHERE  created_at >= (SELECT ts_min FROM var)
   GROUP  BY 1
   ) c USING (day)
LEFT   JOIN (
   SELECT canceled_at::date AS day, count(*) AS deleted
   FROM   entries
   WHERE  canceled_at >= (SELECT ts_min FROM var)
   GROUP  BY 1
   ) d USING (day)
ORDER  BY 1;

CTE var 仅是为了方便一次提供开始时间戳。

The CTE var is only for the convenience to provide the starting timestamp once.

SQL小提琴。

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