Re: how to return field based on field= NULL or not - Mailing list pgsql-general

Juan Backson wrote:
> Hi,
>
> In my table, I have fieldA and fieldB.  At any point in time, only one
> of these fields can have data in it.  The other is NULL.
>
> Instead of "select fieldA, fieldB from table", I want it to return
> either fieldA or fieldB depends on whether it is NULL or not.
>
> The reason is because I want to use "select
> array_to_string(array_accum(field A or field B) ,',') from table.
>
> Is it possible to do it that way?
>
> Thanks,
> JB


The two main ways of doing this are COALESCE(fieldA, fieldB)

http://www.postgresql.org/docs/8.3/interactive/functions-conditional.html#AEN14484

and CASE WHEN fieldA IS NULL THEN fieldB ELSE fieldA END;

http://www.postgresql.org/docs/8.3/interactive/functions-conditional.html#AEN14434