dcrespo wrote:
> Hi everybody,
>
> I'm implementing something like this:
>
> SELECT
> CASE WHEN add_numbers(t1.main_number,t2.main_number)>100
> THEN t1.description1
> ELSE t2.description1
> END AS number_description1,
> CASE WHEN add_numbers(t1.main_number,t2.main_number)>100
> THEN t1.description2
> ELSE t2.description2
> END AS number_description2
> FROM table1 t1, table2 t2;
>
> Is there a way to evaluate the 'CASE WHEN' only once?
Sure, see the implementation of CASE here:
http://www.postgresql.org/docs/8.2/static/functions-conditional.html
Not sure what you are looking for, though, since your condition in both
CASEs above is exactly the same.
--
Guy Rouillier