SET search_path = public;

CREATE or replace FUNCTION a_b (text) RETURNS text AS '
DECLARE

-- Declare aliases for function arguments.
location_in ALIAS FOR $1;
username text;
password text;

BEGIN

     -- This SELECT INTO statement retrieves the ISBN number of the row in
     -- the editions table that had both the book ID number and edition number
     -- that were provided as function arguments.

SELECT into username 1 FROM public;

     -- Check to see if the ISBN number retrieved is NULL.  This will
     -- happen if there is not an existing book with both the ID number
     -- and edition number specified in the function arguments. If the
     -- ISBN is null, the function returns a value of -1 and ends.

return username;
END;
' LANGUAGE 'plpgsql';