实体类型和实体集之间的区别？ [英] Difference between entity type and entity set?

问题描述

什么是属性。实体，实体类型和实体集有什么区别？请举例说明区别。

What is attribute. What is the difference between entity, entity type and entity set? Please explain the difference with an example.

推荐答案

学生

ID名称AGE

1 Ram 12

2 Sam 13

STUDENT

ID Name AGE

1 Ram 12
2 Sam 13

以上是一个示例有两行（1，Ram，12）和（2，Sam，13）的称为Student的表。使用这个我们可以理解区别。

Above is an example of a table called Student having 2 rows (1,Ram,12) and (2,Sam,13) . Using this we can understand the difference.

这是一个真正存在的东西。像tuple1一样，包含有关在现实世界中存在的Ram（id，name和Age）的信息。因此，tuple1是一个实体。因此，我们可以说每个元组是一个实体。

It is something which has real existence. Like tuple1 contains information about Ram(id, name and Age) which has existence in real world . So the tuple1 is an entity. So we may say each tuple is an entity.

是具有共同属性的实体的集合。就像在学生表中一样，每一行都是一个实体，并具有共同的属性。因此 STUDENT 是一种实体类型，其中包含具有属性id，name和Age的实体。数据库中的每个实体类型都由名称和属性列表来描述。所以我们可以说 a表是实体类型

It is collection of entity having common attribute. As in Student table each row is an entity and have common attributes. So STUDENT is an entity type which contains entities having attributes id, name and Age.Also each entity type in a database is described by a name and a list of attribute.So we may say a table is an entity type

它是同一实体的一组实体类型。因此一组学生实体类型的一个或多个实体就是一个实体集。

It is a set of entities of same entity type. so a set of one or more entities of Student Entity type is an Entity Set.

它是实体的财产。例如，在表STUDENT id中，name和Age是实体类型为student的实体的属性。因此，这些是属性。

It is a property of an entity. For example, in table STUDENT id,name and Age are properties of an entity of entity type student. Hence these are attributes.

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