postgresql 8.2 text to boolean

CREATE OR REPLACE FUNCTION public.text2boolean( p_textbool text ) RETURNS boolean AS $BODY$ declare trueArray text[] := array['true', 't', 'y', 'yes', 'on', '1']; falseArray text[] := array['false', 'f', 'n', 'no', 'off', '0']; retValue boolean := false; _p_textbool text; BEGIN _p_textbool := lower($1); if trueArray @> array[_p_textbool] then retValue := true; elsif falseArray @> array[_p_textbool] then retValue := false; else retValue := null; end if; return retValue; END; $BODY$ LANGUAGE plpgsql VOLATILE;