weak-entity | 易学教程

Can a weak entity be involved in both identifying and non-identifying relationships with other tables?

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问题 Obviously a weak entity must be involved (as the child) in one or more identifying relationships, otherwise it would not be weak. But can it, at the same time, also be the child in a non-identifying relationship? 回答1: 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

Example of a strong and weak entity types

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问题 I've tried to look on Google about a decent explanation of weak and strong entity type , but I haven't fully understood them. Could someone give me an example of a strong and weak entity type? 回答1: A weak entity is one that can only exist when owned by another one. For example: a ROOM can only exist in a BUILDING . On the other hand, a TIRE might be considered as a strong entity because it also can exist without being attached to a CAR . 回答2: Just to play with it, question is strong entity

Example of a strong and weak entity types

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I've tried to look on Google about a decent explanation of weak and strong entity type , but I haven't fully understood them. Could someone give me an example of a strong and weak entity type? Paul A weak entity is one that can only exist when owned by another one. For example: a ROOM can only exist in a BUILDING . On the other hand, a TIRE might be considered as a strong entity because it also can exist without being attached to a CAR . Faheem Just to play with it, question is strong entity type and answer is weak. Question is always there, but an answer requires a question to exist. Example: