Three paradigms of relational database

I. First paradigm

In any relational database, the first paradigm (1NF) is the basic requirement for relational schemas, and a database that does not meet the first normal form (1NF) is not a relational database.
The so-called First paradigm (1NF) refers to the fact that each column of a database table is an indivisible basic data item and cannot have multiple values in the same column, that is, an attribute in an entity cannot have multiple values or cannot have duplicate properties. If duplicate attributes are present, you may need to define a new entity, which is composed of duplicate attributes, and a one-to-many relationship between the new entity and the original entity. In the first normal form (1NF), each row of a table contains only one instance of information.

Ii. the second paradigm

The second paradigm (2NF) is established on the basis of the first paradigm (1NF), i.e. satisfying the second normal form (2NF) must first satisfy the first paradigm (1NF). The second normal form (2NF) requires that each instance or row in a database table must be divided by a unique region. It is often necessary to add a column to the table to store the unique identity of each instance.

Iii. Third Paradigm

satisfying the third normal form (3NF) must first satisfy the second normal form (2NF). In short, the third paradigm (3NF) requires that a database table not contain non-primary key information already contained in other tables.

Three paradigms of relational database