弱实体可以同时参与与其他表的识别和非识别关系吗？ [英] Can a weak entity be involved in both identifying and non-identifying relationships with other tables?

问题描述

显然，弱者必须（作为孩子）参与一种或多种识别关系，否则就不会弱。

Obviously a weak entity must be involved (as the child) in one or more identifying relationships, otherwise it would not be weak.

但是，在

推荐答案

是的，弱实体集可以参与非身份识别关系吗？与其他实体的关系。我用孩子来表示您的关系，其中弱实体集位于关系的确定（许多）侧。对弱实体集可以参与的关系的种类没有限制。

Yes, weak entity sets can participate in non-identifying relationships with other entities. By "child", I suppose you mean relationships in which the weak entity set is on the determining (many) side of the relationship. There is no restriction on the kinds of relationships in which weak entity sets may participate.

但是，要小心多个识别关系。尽管弱实体集很容易成为标识关系链的后代，但同一弱实体集上的多个独立标识关系并不常见，这对实体集的概念提出了挑战。参见我对这个问题的回答。

However, watch out for multiple identifying relationships. While a weak entity set can easily be the descendant of a chain of identifying relationships, multiple independent identifying relationships on the same weak entity set are unusual, and challenges the very notion of an entity set. See my answer to this question.

请注意，您的问题标题提到了表之间的关系，这混淆了概念（ER）模型和物理（表格）模型。实体关系用表格表示，但是一般而言关系表也是如此（只有一对一和一对多关系才能被规范化为一个/确定实体集的实体关系，多对多和三元关系更高的关系仍然需要他们自己的表）。

Note that your question title mentions relationships between tables, which confuses conceptual (ER) and physical (tabular) models. Entity relations are represented by tables, but so are relationship relations in general (only one-to-one and one-to-many relationships can be denormalized into the entity relation of a/the determining entity set, many-to-many and ternary and higher relationships still require their own tables).

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