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

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> -----Original Message-----
> From: Andre Lopes [mailto:lopes80andre@xxxxxxxxx] 
> 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

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