📜  ER 模型和 RDBMS 之间的区别

📅  最后修改于: 2021-09-10 03:00:39             🧑  作者: Mango

1. ER(实体-关系)模型:
ER 模型代表实体关系模型。它通过给出系统实体之间的关系来指定数据库的结构。实体集是一组彼此相似的实体。它被认为是一种概念设计,可以进一步用于实现数据库。借助图形表示,它可以帮助我们以简单的方式理解不同实体之间的关联。 ER模型一般是在制作数据库之前构建的。 ER 模型用于描绘现实世界的实体以及它们之间的关联。

2. RDBMS(关系数据库管理系统):
RDBMS 代表关系数据库管理系统,它是根据 EFCodd 给出的模型为关系数据库设计的数据库管理系统。关系数据库以表格的形式以结构良好的格式存储数据,这使得在需要时更容易检索数据。它具有用于检索数据的高效查询处理技术。在 RDBMS 中,可以存在多个表并且这些表可以相互关联。 RDBMS 是当今最常用的数据库管理模型。

ER 模型和 RDBMS 之间的区别:

S.NO. ER Model RDBMS
1. ER model is a high level data model which tells us about the relationship between the entities. RDBMS is a database management system which has a collection of tables which are related to each other.
2. ER model is easier to understand as it is in pictorial form. RDBMS is comparatively more complex than ER model.
3. ER model is made before the construction of database to get an idea of the database. RDBMS is an implementation of the ER diagram.
4. ER model has attributes, entities and relationships as its main components. RDBMS has tuples, domains, keys as its main components.
5. ER model has mapping cardinalities. RDBMS doesn’t have mapping cardinalities.
7. It requires comparatively less skillful people to construct the ER model. It requires more skillful people to deal with the database systems.