Three Paradigms of database table design

The three paradigms of database design (nomorlization)

1NF: Atomicity, that is, each field cannot be split.

2NF: Uniqueness, that is, each table only describes an entity, the entity must have a primary key, the non-primary key to fully rely on the primary key, because it is said to be completely dependent, because in the case of a combined primary key, the non-primary keyword can not rely on only some keywords.

3NF: A table cannot contain information about non-primary key fields that already exist in other tables, that is, it can only contain primary key information for other tables, so that is the primary foreign key, the connection between tables can be made through the primary foreign key (join), and 3NF is mainly to reduce data redundancy.