流畅的 Nhibernate 映射以避免空引用
我们有一个 Order 实体和一个 CreditCard 实体。
订单可以有 0 或 1 个信用卡。
CreditCard 可以有 1 个或多个 Orders
我理解这是一对多关系。但我们预计大多数订单不会使用信用卡支付，因此订单表将充满空引用。我的理解是这是一个不好的做法。
是否可以通过其他方式设计数据库/实体/映射来避免这种情况？
We have an Order entity and a CreditCard entity.
The Order can have 0 or 1 CreditCards.
The CreditCard can have 1 or more Orders
I understand this to be a one-to-many relationship. BUT we anticipate for the majority of Orders to not be paid using a CreditCard, hence the Order table will be full of null references. My understanding being that this is a bad practice.
Is it possible to design the database/entities/mappings some other way to avoid this?
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我认为你想多了。如果是我，我只会在我的订单中引用信用卡，而在我的信用卡实体中，我将有一个 HasMany 到订单。如果您愿意，可以在订单中添加 HasCreditCard 布尔值，仅检查订单中的信用卡对象是否为空。
I think that you are over thinking this. If it were me I would just have a Reference to a credit card in my order and in my credit card entity I would have a HasMany to Orders. If you want you can have a HasCreditCard boolean in your order that just checks if the credit card object in your order is null or not.