function obtenerMaximo($field)
 {
     $maximo = new Tab_docprestamo();
     $verificar = $maximo->dbselectAll();
     $t = 0;
     foreach ($verificar as $count) {
         $t++;
     }
     if ($t > 0) {
         $max = $maximo->dbSelectBySQL("SELECT* from tab_docprestamo\r\n                where {$field} = (select max({$field}) from tab_docprestamo)");
         $mx = $max[0];
         $incre = $mx->dpr_orden + 1;
         return $incre;
     } else {
         return 1;
     }
 }