Re: Interval Question

Apparently, if DateStyle is set to Sql, it always returns the absolute value.
Is this due to some Sql standard or is it a bug?

On Tuesday 11 January 2005 10:19 am, Tom Lane saith:
> Terry Lee Tucker <terry@esc1.com> writes:
> > I thought that subtracting the larger interval from
> > the small would return this but it is always the absolute value.
>
> Eh?
>
> regression=# set DateStyle TO ISO;
> SET
> regression=# select '@ 3 days 4 hours 17 mins'::interval -
> regression-# '@ 3 days 6 hours 17 mins'::interval;
>  ?column?
> -----------
>  -02:00:00
> (1 row)
>
> regression=# set DateStyle TO postgres;
> SET
> regression=# select '@ 3 days 4 hours 17 mins'::interval -
> regression-# '@ 3 days 6 hours 17 mins'::interval;
>    ?column?
> ---------------
>  @ 2 hours ago
> (1 row)
>
> and as for detecting whether it's negative,
>
> regression=# select ('@ 3 days 4 hours 17 mins'::interval -
> regression(# '@ 3 days 6 hours 17 mins'::interval) < '0'::interval;
>  ?column?
> ----------
>  t
> (1 row)
>
>             regards, tom lane
>
> ---------------------------(end of broadcast)---------------------------
> TIP 9: the planner will ignore your desire to choose an index scan if your
>       joining column's datatypes do not match

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