更新事物列表，而无需点击所有条目

我在数据库中有一个用户可以订购的列表.

I have a list in a database that the user should be able to order.

itemname|  order value (int)
--------+---------------------         
salad   |  1
mango   |  2
orange  |  3
apples  |  4

从数据库加载时，我只是order by order_value.

On load from the database, I simply order by order_value.

通过拖放，他应该可以移动apples，使其出现在列表的顶部.

By drag 'n drop, he should be able to move apples so that it appears at the top of the list..

itemname|  order value (int)
--------+---------------------         
apples  |  4
salad   |  1
mango   |  2
orange  |  3

好的.因此，现在在内部，我必须更新每个列表项！如果列表包含20或100个项目，那么对于简单的拖动操作来说，这是很多更新.

Ok. So now internally I have to update EVERY LIST ITEM! If the list has 20 or 100 items, that's a lot of updates for a simple drag operation.

itemname|  order value (int)
--------+---------------------         
apples  |  1
salad   |  2
mango   |  3
orange  |  4

我只希望进行一次更新.我想到的一种方法是，内部订单"是否为double值.

I'd rather do it with only one update. One way I thought of is if "internal Order" is a double value.

itemname|  order value (double)
--------+---------------------         
salad   |  1.0
mango   |  2.0
orange  |  3.0
apples  |  4.0

在执行拖放n'操作之后，我指定apples的值小于它出现在以下项之前的值:

SO after the drag n' drop operation, I assign apples has a value that is less than the item it is to appear in front of:

itemname|  order value (double)
--------+---------------------         
apples  |  0.5
salad   |  1.0
mango   |  2.0
orange  |  3.0

..如果将某个项目拖到中间的某处，则它的order_value大于它在..之后出现的项目.在这里，我将orange移到了salad和mango之间:

.. and if an item is dragged into the middle somewhere, its order_value is bigger than the one it appears after .. here I moved orange to be between salad and mango:

itemname|  order value (double)
--------+---------------------         
apples  |  0.5
salad   |  1.0
orange  |  1.5
mango   |  2.0

有什么更好的方法吗?