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是否在结构更新中将田地划归一?
原标题:Does ordering matter for fields in a SQL update?

在我看来,如果你在更新说明中相互依赖的领域,我不敢确保能够保证秩序(或需要!)。

例如,你说有以下最新情况:

UPDATE Table
SET NewValue = OldValue, OldValue = NULL

NewValue是否总是首先更新,然后将旧Value废除? 或者,处理过程中的行文(或纸张或桌子等)状况是不可改变的,因此所有变动都是在计算变化之前作出的。

最佳回答

建立了一个新的虚拟增长,然后以原子的方式取代现有的增长。 在数据投入使用之前,你可以查阅所有现有数值。

<><>Edit>/strong> 情况并非如此。

问题回答

是的,该系统将更新新韦洛,以了解在实施询问之前在旧韦里存在的价值,然后将旧韦洛定为无效。 事实上,你们可以放弃这样的价值观:

UPDATE Table
SET NewValue = OldValue, OldValue = NewValue

为什么你不简单地把这个问题作为两个单独的问题处理?

begin transaction
UPDATE Table
SET NewValue = OldValue

UPDATE Table
SET OldValue = NULL
commit

还是这种家务工作?





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