Between needs and features, on the other hand, there is many to many mapping.
另一方面，在需要与特性之间，是多对多的映射。
Partial Key Joins occur when there is an implicit many to many relationship between a dimension and a fact.
当一个维度和一个事实之间有一个隐式的多对多关系时会出现PartialKeyJoins。
To map these relationships effectively, we must understand the differences between them, how to implement relationships generally, and how to implement many-to-many relationships specifically.
要有效地映射这些关系，必须理解它们之间的差异、如何实现一般的关系，以及如何实现特定的多对多关系。
If you have some experience modeling data for relational databases, you know that many-to-many relationships between different relational entities appear all the time.
如果您有关系数据库数据的建模经验，那么您就会知道不同关系实体之间的多对多关系随时会出现。
And of course, I'll be modeling it as a many-to-many relationship because I hope my runners will run more than one race.
当然，我将把它建模为一个“多对多”关系，因为我希望我的参赛者可以参加多项比赛。
Each many-to-many association maps to a distinct table.
每个多对多的关联映射到唯一的表。
The disadvantage of this schema is a slightly increased complexity with a many-to-many relationship between the fact table and the UCAT table.
这种模式的缺点是稍微增加了一点复杂性，事实表与U cat表之间存在多对多的关系。
Instead of taking this approach, we will use a more traditional many-to-many model, as shown in Listing 2.
我们不会采取这种方法，而是使用更传统的多对多模型，如清单2所示。
Transparent, providing cross domain visibility via many-to-many artifact relationships.
透明的，以多对多的工件关系支持跨领域可见性。
More than the simple mechanics of many-to-many relationships, I hope that you picked up on some of the subtleties of creating them as well.
除了简单的多对多关系以外，希望您还能从本文了解一些创建多对多关系的出色技巧。
You would probably need to set up a many-to-many relationship with a join table, requiring several joins to determine the actors for a particular movie.
您可能需要使用一个联接表设置一个多对多关系，这需要几个联接来确定某个电影的演员。
Classic database normalization would say to create a pizza table, and then a many-to-many table relating pizza IDs to topping IDs.
典型的数据库标准会建议需要先创建一张比萨表，然后再创建一张将比萨id与浇头id关联起来的多对多表。
So you need a table to connect a book to an author, and you must allow those connections to be many-to-many.
因此需要一个表连接图书和作者，而且这种连接必须是多对多的。
On the other hand, if one author can have multiple books, and one book can also have multiple authors, it's called a many-to-many relation.
另一方面，如果一个作者拥有多本书籍，一本书又有多个作者，就称为多对多关系。
Many-to-many interactions: one or more events can affect one or more subscribers.
多对多的交互：一个或多个事件会影响一个或多个订阅者。
When complex, embedded software is involved, this leads to a many-to-many decision tree with thousands — perhaps millions — of possible allocations.
当涉及到复杂的、嵌入式软件时，就会导致一个上千——或许上百万种可能分配的多对多决策树。
Many-to-many relations require a special mapping and are handled individually in another relation.
多对多关联需要一个特殊映射，它在另一个关联中被单独处理。
Sometimes, relationships expressed during conceptual data modeling (in particular many-to-many relationships) are shown in the logical model as entities themselves.
有时候，概念数据建模期间表达的关系（特别是多对多关系）在逻辑模型中被显示为实体本身。
So there is a many-to-many relationship between code blocks and business operations.
因此代码块与业务操作之间存在多对多的关系。
Another possibility is to limit the scope of the document so that the many-to-many relationship disappears.
另一种可能性是限制文档的作用域，以使多对多关系消失。
The case of the many-to-many associations is not discussed here, as its implementation is quite similar to the relations we presented before.
多对多关联的情况这里没有讨论，因为它的实现与我们前面介绍的大同小异。
Many-to-many associations (handled by another relation) are outside the scope of this article.
多对多关联（由另一个关联处理）不在本文讨论范围之内。
The purpose of this relation is to filter the many-to-many associations, which are handled by another relation.
此关联的目的是过滤掉多对多关联，它由另一个关联处理。
So, how do we map a many-to-many association?
那我们怎样映射多对多关系呢？
In Figure 11 you see how to use an associative table to implement a many-to-many relationship.
图11中，可以看到如何使用关联表来实现多对多关系。
The easiest solution to the problem is to simply discard some of the information that would normally need to be linked through a many-to-many relationship.
该问题最简单的解决方案是只要废弃某些多对多关系通常需要通过链接的信息。
There is really a many-to-many relationship between feeds and accounts.
提要与帐户之间存在多对多关系。
A many-to-many association is mapped to a distinct table.
一个多对多关联被映射到一个单独的表。
Later, in "Many-to-many relationships with a dollop of Ajax," you used GORM to model increasingly sophisticated class relationships.
之后的“使用Ajax实现多对多关系”教您使用GORM建模越来越复杂的类关系。
Thus, pub/sub-based service interactions can support true many-to-many relationships.
因此，基于pub/sub 的服务交互能够支持真正的多对多关系。
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