每个组的成员都有不同的过滤器

Question

对于每个主题，我想在特定日期后过滤他们的记录。但是，我想用作过滤器的日期对于每个主题都是不同的。有没有办法按主题分组，然后为每个组使用不同的 having 从句？

Answer 1

你可以这样做：

select tbl.subject
      ,count(*) as record_count
      -- add other aggregate functions as required
from thetable tbl
     join (values
     ('somesubject' ,'2005-04-03')
    ,('othersubject','2008-07-06')
    ,('yetanother'  ,'2013-12-11')
    -- add as many subjects as required
     ) cutoff(subject,min_dt) on cutoff.subject = tbl.subject and cutoff.min_dt::date <= tbl.date_column
group by tbl.subject

每个组的成员都有不同的过滤器

A different filter for each group by member

postgresql

postgresql-9.1