Five paradigms in Database Design (this article is reposted and added to favorites)

Five paradigms in Database Design

First paradigm:
Each row in a table must have only unique row values. Each column in a row has only unique values and is atomic.
The first paradigm is to remove duplicate groups by placing duplicate groups in each independent table and associating these tables through one-to-Multiple Association.

Second paradigm:
The second paradigm requires that the non-primary key column is a subset of the primary key, and the activity of the non-primary key column must be completely dependent on the entire primary key. A primary key must have a unique element. A primary key can consist of one or more columns with unique values. Once created, the primary key cannot be changed. The foreign key is associated with the primary key of a table. The relationship between the primary and Foreign keys indicates a one-to-many relationship.
The second paradigm deals with the deletion of redundant data. When the information in a table depends on other columns in the table that are not the primary key, the second paradigm is usually violated.

Third paradigm:
The third paradigm requires that non-primary key columns do not depend on each other.
The third paradigm rule searches to eliminate the primary key attributes of tables that are not directly dependent on the first and second paradigms. We have created a new table for all the information not associated with the table's primary key. Each new table stores information from the source table and the primary keys they depend on.

Fourth paradigm:
The fourth paradigm prohibits one-to-multiple relationships between primary key columns and non-primary key columns from being constrained.

Fifth paradigm:
The fifth paradigm divides the table into as small blocks as possible, in order to exclude all redundancy in the table.

During database design, you should always pay attention to these paradigms. The fifth paradigm is the most difficult to implement. However, you still need to implement these functions as much as possible.