Re: creating a function returning FALSE on NULL input ?

On Nov 7, 2012, at 0:33, Yvon Thoraval <yvon(dot)thoraval(at)gmail(dot)com> wrote:

> I'd like to create a function :
> returning true if the length of the text arg is greater than 0 ;
> false otherwise ;
>
> and also returning false when arg is NULL, then i wrote :
>
> CREATE FUNCTION has_infos(text) RETURNS boolean AS 'select character_length($1) > 0;' LANGUAGE SQL IMMUTABLE RETURNS FALSE ON NULL INPUT;
>
> where i get the error :
>
> ERROR: syntax error at or near "FALSE"
> LINE 1: ...r_length($1) > 0;' LANGUAGE SQL IMMUTABLE RETURNS FALSE ON N...
>
> with "RETURNS NULL on NULL INPUT", that's OK.
>
> --
> Yvon
>

You have to allow for null input and deal with it in the function body. Usually via a CASE structure.

David J.