Re: NEWBIE: How do I get the oldest date contained in 3 tables

From: Brent Wood <b(dot)wood(at)niwa(dot)co(dot)nz>
To: Lorenzo Thurman <lorenzo(at)diespammerhethurmans(dot)com>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: NEWBIE: How do I get the oldest date contained in 3 tables
Date: 2007-04-09 22:23:57
Message-ID: 461ABCFD.7050102@niwa.co.nz
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Lorenzo Thurman wrote:
> I have three tables using date fields. I want to retrieve the oldest
> date contained in the tables. Can someone show me an example of a
> query that would do that?
You could write a custom function doing the same sort of thing, or
(perhaps more portable) use generic sqls & views like:

create view min_dates as
select min(date1) from table1as date_1
union
select min(date2) from table2 as date_1
union
select min(date3) from table3 as date_1;

then either:

select min(date_1) from min_dates;

or

create view min_date as
select min(date_1) as min_date
from min_dates;

then just:

select min_date from min_date;

Cheers

Brent Wood

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