实体、实体集和属性之间有什么区别?
在做课堂作业时,我突然发现自己被一句话难住了:
作业还必须包含至少 4 个具有有意义数据的附加实体(不是表格)
。
我必须为博物馆创建一个示例数据库,用于对各种作品进行编目,为它们分配主题,并按主题创建展览。这些表中的每一个都必须有 10 个条目,所以我很困惑这 4 个附加实体可能会问什么..
帮助?
While doing a homework for a class I suddenly found myself stumped by a sentence:
The work must also contain at least 4 additional entities(not tables) with meaningful data
.
I had to create an example database for a museum, for cataloging various pieces, assigning themes to them, and creating expositions by themes. Each of these tables already must have 10 entries, so I am quite confused what could be asked by the 4 additional entities..
Help?
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根据我的经验,这两者始终是同义词(实体和表)。我以前听说人们将数据称为实体,但通常实体指的是表。我的经验主要是使用 SQL Server 和 Microsoft Dynamics CRM。你在什么平台工作?
实体集通常表示实体数据的切片,即居住在湾区的所有联系人都将是该联系人实体的实体集。
属性属于一个实体并描述该实体的列。我一直听说实体属性和表列命名法一起使用,但尚未看到两者之间的区别。
In my experience the two have always been synonymous (entity and table). I've heard people refer to the data as an entity before but normally entity is referring to the table. My experience is mostly with SQL server and Microsoft Dynamics CRM. What platform are you working in?
An entity set usually represents a slice of an entities data, i.e. all contacts who live in the bay area would be an entity set of the contact entity.
Attributes belong to an entity and describe the columns of the entity. I've always heard the entity-attribute and table-column nomenclatures used together but have yet to see a difference between the two.