DBMS的数据模型和数据库模式:间的区别
问题说明
我知道数据模型基本上是ER模型和关系模型两种类型。数据库模式也是物理和逻辑两种类型。
I know the Data Model is basically two types ER-Model and Relational Model & Database schema is also two type Physical and logical.
但是基于它们在DBMS中的操作，我不明白它们之间有什么区别？
But I can not understand what is the difference between them based on their operation in DBMS?
正确答案
模式是数据库的蓝图，它指定将显示哪些字段以及字段的类型。例如，一个 employee 表将具有一个 employee_ID 列，该列由10位数字字符串和一个 employee_Name 列（包含45个字符）。
A schema is a blueprint of the database which specifies what fields will be present and what would be their types. For example an employee table will have an employee_ID column represented by a string of 10 digits and an employee_Name column with a string of 45 characters.
数据模型是一个高级设计，它决定了模式中可以包含的内容。它为数据库用户提供了一个概念框架，其中我们指定了数据库用户的数据库要求以及满足这些要求的数据库结构。
Data model is a high level design which decides what can be present in the schema. It provides a database user with a conceptual framework in which we specify the database requirements of the database user and the structure of the database to fulfill these requirements.
数据模型可以例如，是一个关系模型，其中的数据将以表的形式组织，而该模型的架构将是属性及其对应域的集合。
A data model can, for example, be a relational model where the data will be organised in tables whereas the schema for this model would be the set of attributes and their corresponding domains.
参考文献： 了解架构和数据库系统概念（H Korth和Silberschatz）
References: Understanding the schema and Database System Concepts (H Korth and A Silberschatz)
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