Re: [SQL] datediff function

From: Herouth Maoz <herouth(at)oumail(dot)openu(dot)ac(dot)il>
To: "tjk(at)tksoft(dot)com" <tjk(at)tksoft(dot)com>, tpham(at)mail(dot)priority(dot)net (Pham Thinh)
Cc: pgsql-sql(at)postgreSQL(dot)org
Subject: Re: [SQL] datediff function
Date: 1999-08-17 11:05:02
Message-ID: l03130300b3def2007db9@[147.233.159.109]
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At 02:26 +0300 on 17/08/1999, tjk(at)tksoft(dot)com wrote:

>
> I think what you are looking for is age()
> E.g.
>
> "update schedule set purged = 0 where age('now',dayin) > timespan('30
>days'::reltime)"
>
> Presuming a table such as this:
>
> create table schedule (purged int, dayin datetime);
>
> This replaces "day" and "timein" with "dayin."

Basically correct, but if there is an index on dayin, it won't be used. The
best query to do would be

WHERE dayin > 'now'::datetime - '30 days'::timespan;

Herouth

--
Herouth Maoz, Internet developer.
Open University of Israel - Telem project
http://telem.openu.ac.il/~herutma

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