禁止关系甲骨文学院 [英] Barred relationship Oracle academy

问题描述

我正在上有关数据库设计和开发的Oracle Academy课程，他们正在谈论ERD设计部分中的禁止关系，但我只是不明白它们的含义.我到处都看过，但找不到很好的例子，只是不明白.有没有人可以通过一个很好的例子向我解释它的工作原理和作用?

I'm doing the Oracle Academy course about Database design and development and they are talking about barred relationships in the ERD design part, but I just can't understand what they mean. I looked everywhere but I can't find a good example and I just don't get it. Is there someone that can explain to me with a good example how it works and what it does?

推荐答案

我认为您所引用的文档是

I think the document you are referring to is this one.

本文对禁止的关系"的含义进行了解释.这是关于多对多表示的具体表示.

What they mean with the "barred relationships" is explained in the text. This is about the concrete representation of a Many-to-Many representation.

原来的M:M关系已变成两个1:M关系.

The original M:M relationship has become two 1:M relationships.

交集实体的UID是什么?

What would be the UID of the intersection entity?

以下是以下部分:禁止的关系

交集实体的唯一标识符(UID)通常来自原始关系，并由条形图表示.在这种情况下，从原始实体到相交实体的关系称为禁止"关系.

The unique identifier (UID) of the intersection entity often comes from the originating relationships and is represented by the bars. In this case, the relationships from the originating entities to the intersection entity are called "barred" relationships.

这是因为它们首先使纯模型表示成为可能.为了在关系模型(我想是Oracle Enterprise Database)中有一个可行的实现，需要在每个实体中都有一个唯一的标识符，并引入一个新的实体和相对关系(禁止关系).

This is because they make in the first place a pure modeling representation. To have a working implementation in a relation model (I guess Oracle Enterprise Database), there is a need to have a unique identifier in each entity and to introduce a new entity and relative relationships (barred relationships).

我将不对UML，ERD和关系模型之间的关系做任何长篇幅的解释.实体关系模型是不同于关系模型的数据表示.从关系的角度来看，要综合(但不是很尖锐)，这是一种抽象表示，需要为关系实现进行改进.

I won't make any long explanation on the relationship between UML, the ERD and the relational model. The Entity-relationship model is a representation of data distinct from the relational model. To be synthetic (but not sharp), in a relational point of view, this is an abstract representation that needs to be improved for a relational implementation.

我想说几句，我猜你是法语，并且会很容易地以这种方式理解:在 Merise 方法，这是从概念模型(MCD)到逻辑模型(MLD)的过渡.

I a few words, I guess you are French and will understand easily that way: in the Merise method, this is the transition from the conceptual model (MCD) to the logical model (MLD).

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