$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 .= ')';