On Fri, Mar 09, 2007 at 23:07:26 -0300,
Jorge Godoy <jgodoy@gmail.com> wrote:
>
> But how to get the date if the first day of the week is a Wednesday? This
> example is like the ones I've sent with separate queries that needed being
> combined -- in a function, probably -- to get the desired result.
If you want to group on weeks that start on Wednesdays add 5.
postgres=# select date_trunc('week', '2007-03-07'::date + 5);
date_trunc
------------------------
2007-03-12 00:00:00-05
(1 row)
postgres=# select date_trunc('week', '2007-03-06'::date + 5);
date_trunc
------------------------
2007-03-05 00:00:00-06
(1 row)
postgres=# select date_trunc('week', '2007-03-08'::date + 5);
date_trunc
------------------------
2007-03-12 00:00:00-05
(1 row)