$consulta = 'SELECT MAX(cladocumento) AS max '
                . 'FROM empleadosdocumentos '
                . 'WHERE clacliente = ' . $cliente 
                . ' GROUP BY claempleado, clatipodocumento';
        $sentencia = $conexion->prepareStatement($consulta);
        $resultset = $sentencia->executeQuery();
        
        $in = 'cladocumento in (-1';
        while( $resultset->next() ){
            $in .= ',' .$resultset->getInt('max');
        }
        $in .= ')';