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Re: creating a function returning FALSE on NULL input ? - Mailing list pgsql-general

From Yvon Thoraval
Subject Re: creating a function returning FALSE on NULL input ?
Date
Msg-id CAG6bkBwoS7pO+MhN3CJfZt+NUw-fYxOoAPoSxzoY2QG0RJ=-hw@mail.gmail.com
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In response to Re: creating a function returning FALSE on NULL input ?  (David Johnston <polobo@yahoo.com>)
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Fine thanks,I've found that way :
recettes=> DROP FUNCTION has_infos(text);
DROP FUNCTION


recettes=> CREATE FUNCTION has_infos(text DEFAULT '') RETURNS boolean AS $BODY$
recettes$> BEGIN
recettes$> IF character_length($1) > 0 THEN
recettes$>   RETURN TRUE;
recettes$> ELSE
recettes$>   RETURN FALSE;
recettes$> END IF ;
recettes$> END
recettes$> $BODY$
recettes-> LANGUAGE 'plpgsql' ;
CREATE FUNCTION

I've verified, it works on NULL input...



2012/11/7 David Johnston <polobo@yahoo.com>
On Nov 7, 2012, at 0:33, Yvon Thoraval <yvon.thoraval@gmail.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.




--
Yvon


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