数据库范化 database normalization

最新推荐文章于 2025-09-14 22:40:40 发布

转载最新推荐文章于 2025-09-14 22:40:40 发布 · 4.2k 阅读

文章标签：

#database #数据库 #attributes #structure #build #table

数据库规范化是构建逻辑合理、便于维护的数据库结构的关键步骤。本文详细阐述了第一范式、第二范式和第三范式的概念及应用，解释了规范化过程中的常见错误及其解决方案。

Database normalization is useful for several reasons:
       a. It helps to build a structure that is logical and easy to maintain.
        b. Normalized databases are the industry standard.
        c. Retrieving data will be easier.

First Normal Form means that the database doesn't contain any repeating attributes.
Violations of Second Normal Form occur when the table contains attributes that depend on a portion of the primary key.
Second Normal Form violations can exist only when you have a multi-column primary key.
Third Normal Form violations occur when a transitive dependency exists.
All attributes in entities (columns in tables) must be dependent upon the primary key or one of the candidate keys and not on other attributes.