__SQL_GET_STRING(wartosc,
"SELECT MAX(co_%s_%s_wartosc(id,typ))
            FROM co_%s_%s
            WHERE nazwa='%s' AND
                 data_od<='%s' AND
                 data_do>'%s'",
par_area,par_class,par_area,par_class,par_nazwa,par_data,par_data)

__RETURN_STRING(wartosc)