entity - Entity in entity relationship diagram

Question

According to wikipedia "An entity may be defined as a thing which is recognized as being capable of an independent existence and which can be uniquely identified". I don't get this independent existance because I've been given examples of entities such as "fees" or a "house sale", you can't have fees without taking a "class" and no "house sale" without having a house. Where am I confused?

Answer 1

我同意你的看法——我认为独立存在并没有增加太多的定义。

最好将实体视为您可能希望存储有关信息的东西，例如

order
order history
customer
supplier
order item
address
address history

NB 实体永远不会多元化

Answer 2

根据您文章的德语版本，实体可以描述为现实世界中的“对象”，可以用某些属性来描述。
例如，驾照可以是一个实体，即使它相当抽象，因为它可以用属性来描述。