Re: How to obtain the maximum value of a date, between 3 tables...

> -----Original Message-----
> From: Andre Lopes [mailto:lopes80andre@gmail.com]
> Sent: Wednesday, December 08, 2010 8:16 AM
> To: postgresql Forums
> Subject: How to obtain the maximum value of a date, between 3
> tables...
>
> Hi,
>
> I need to obtain the maximum value of a date, but that
> comparison will be made between 3 tables... I will explain
> better with a query...
>
> [code]
> select
> a.last_refresh_date as d1, ae.last_refresh_date as d2,
> ha.last_refresh_date as d3 from tbl1 a join tbl2 ae on
> a.id_anuncio_externo = ae.id_anuncio_externo join tbl3 ha on
> a.id_anuncio_externo = ha.id_anuncio_externo [/code]
>
> My question is how is the best way to obtain with date is the
> greatest, d1, d2 or d3
>
> Can you guys give me a clue.
>
> Best Regards,
>
>
>

This:

SELECT GREATEST(q.d1, q.d2, q.d3) FROM
(select
  a.last_refresh_date as d1, ae.last_refresh_date as d2,
  ha.last_refresh_date as d3 from tbl1 a join tbl2 ae on
  a.id_anuncio_externo = ae.id_anuncio_externo join tbl3 ha on
  a.id_anuncio_externo = ha.id_anuncio_externo) q;

should do it.

Igor Neyman