Re: How to get the previous date?

On 2009-10-14, Shruthi A <shruthi(dot)iisc(at)gmail(dot)com> wrote:
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> Hi,
>
> I'm using Enterprise DB PostgresPlus version 8.3.
> Is there is a simple function or command like previous_date(mydate) which
> when passed a particular date, simply returns the previous date? I tried
>
> mydate - 1
>
> but this doesnt work.

it should, if mydate is a date variable.

if it's some sort of timestamp more care is needed

mytimestamp - interval'1 day'

also don't use interval'24h' unless you want 24h, because not all days are 24h

select timestamptz'2009-09-28 00:30' - interval'24 h' ;
?column?
------------------------
2009-09-26 23:30:00+12

(the interval crosses the local start of DST)