Question

在Postgres中，我汇总了总金额，将天数分开，然后将这些数据转储到图表中。示例查询如下所示：

SELECT 
EXTRACT(YEAR FROM post_created_date) as report_year, EXTRACT(WEEK FROM post_created_date) AS regweek, COUNT(post_id) as post_count 
FROM TableA 
GROUP BY report_year, regweek

这很好用，但有些日子里没有数据，给出了图表空白

1/14  -  5
1/15  -  7
1/18  -  4

如何在该日期也包含没有事件报告0的日期？

Answer 1

为此，您需要使用left outer join。我们的想法是创建年和周的所有组合，然后加入您的查询。使用generate_series()的Postgres非常容易。类似的东西：

select yw.yr, yw.wk, coalesce(r.post_count, 0) as post_count
from (select distinct EXTRACT(YEAR FROM post_created_date) as yr,
             generate_series(1, 52) as wk
      from TableA
     ) yw left outer join
     (SELECT EXTRACT(YEAR FROM post_created_date) as report_year,
             EXTRACT(WEEK FROM post_created_date) AS regweek, COUNT(post_id) as post_count 
      FROM TableA 
      GROUP BY report_year, regweek
     ) r
     on yw.yr = report_year and yw.wk = regweek;

Postgres在聚合时填写空数据

1 个答案: