数据库三大范式最简单的解释
关系数据库中的关系必须满足一定的要求，即满足不同的范式。目前关系数据库有六种范式：第一范式（1NF）、第二范式（2NF）、第三范式（3NF）、第四范式（4NF）、第五范式（5NF）和第六范式（6NF）。满足最低要求的范式是第一范式（1NF）。在第一范式的基础上
关系数据库中的关系必须满足一定的要求，即满足不同的范式。目前关系数据库有六种范式：第一范式（1NF）、第二范式（2NF）、第三范式（3NF）、第四范式（4NF）、第五范式（5NF）和第六范式（6NF）。满足最低要求的范式是第一范式（1NF）。在第一范式的基础上进一步满足更多要求的称为第二范式（2NF），其余范式以次类推。一般说来，数据库只需满足第三范式（3NF）就行了。
很多资料上的范式都讲的很难理解，这里总结一下三大范式，便于读者简易的理解。
1NF：字段是原子性的，不可分;
2NF：有主键，非主键字段依赖主键。确保一个表只说明一个事物
3NF：非主键字段不能相互依赖。 每列都与主键有直接关系，不存在传递的依赖
第一范式：不符合第一范式的例子：
表：字段1、 字段2(字段2.1、字段2.2)、字段3 ......
第二范式：不符合第二范式的例子:
表：学号、课程号、姓名、学分;
这个表明显说明了两个事务:学生信息, 课程信息;由于非主键字段必须依赖主键，这里学分依赖课程号，姓名依赖与学号，所以不符合二范式。
第三范式：不符合第三范式的例子:
表：学号、姓名、 年龄、 所在学院、学院联系电话、学院联系电话
存在依赖传递: (学号) → (所在学院) → (学院地点, 学院电话)
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