Re: Rounding

Chris Boget wrote:
> Is there a way, internal in PG, that you can round to the
> nearest half decimal (rounded up or down)?  ie, I want to
> round 97.37 to 97.5 or 97.81 to 98.
> The closest thing I could see in the docs would take the
> 97.33 turning it into 97.4 and 97.81 to 97.8.  Is there some-
> thing I am missing?
>

I don't know of a built in way to "round to the nearest half increment",
which it seems you want to do. You could always write a function for it.
e.g.:

create or replace function nearesthalf(float8)
returns float8 as '
select case
             when ($1 - floor($1)) <= 0.25 then floor($1)
             when ($1 - floor($1)) > 0.75 then ceil($1)
             else (ceil($1) + floor($1)) / 2
        end
' language sql;

regression=# select nearesthalf(97.17);
  nearesthalf
-------------
           97
(1 row)

regression=# select nearesthalf(97.37);
  nearesthalf
-------------
         97.5
(1 row)

regression=# select nearesthalf(97.67);
  nearesthalf
-------------
         97.5
(1 row)

regression=# select nearesthalf(97.77);
  nearesthalf
-------------
           98
(1 row)

Is this what you were looking for?

Joe