linq to sql loadwith vs associatewith [英] linq to sql loadwith vs associatewith

问题描述

loadwith和associatewith之间的区别是什么.从我阅读的文章看来，loadwith似乎用于加载附加数据(例如，客户的所有订单).而AssociateWith用于过滤数据.

what is the difference between loadwith and associatewith. From the articles i read it seems that loadwith is used to load addition data (eg all orders for the customers). While AssociateWith is used to filter data.

这是正确的理解吗?如果有人可以通过基于示例的解释对此进行解释，那也将是很好的.

Is that a correct understanding? Also it will be nice if someone can explain this with an example based explanation.

推荐答案

LoadWith用于执行关联的渴望加载，而不是默认的惰性加载 >.

LoadWith is used to perform an eager load of an association as opposed to the default lazy load.

通常，关联是在您第一次引用它们时加载的.这意味着，如果选择100个Order实例，然后对它们的每个Details进行操作，则实际上是对数据库执行101个SELECT操作.另一方面，如果LoadOptions指定LoadWith<Order>(o => o.Details)，则所有操作都在添加了JOIN的单个SELECT中完成.

Normally, associations are loaded the first time you reference them. That means if you select 100 Order instances, and then do something with each of their Details, you're actually performing 101 SELECT operations against the database. On the other hand, if the LoadOptions specify LoadWith<Order>(o => o.Details), then it's all done in a single SELECT with an added JOIN.

AssociateWith对加载关联的 没有任何影响，只是加载了什么.每次加载关联时，它都会添加一个WHERE子句.

AssociateWith doesn't have any effect on when the association is loaded, just what is loaded. It adds a WHERE clause every time you load an association.

正如您所说，AssociateWith用于自动 过滤数据.通常，如果您知道一个关联具有大量元素并且只需要它们的特定子集，就可以使用它.同样，它主要是性能优化，只是另一种.

As you say, AssociateWith is used to automatically filter data. Typically you'd use this if you know that an association has a very large number of elements and you only need a specific subset of them. Again, it's mainly a performance optimization, just a different kind.

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