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This article mainly introduces the database three paradigms and anti-paradigm is, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand.

In the daily development process, we need to operate the Mysql database, which involves the construction of tables. How to create a well-structured database table, we need to follow the following three database paradigms.

1. The first paradigm

Ensure the atomicity of each column (field) in the data table.

If each field in the data table is the smallest data unit that can no longer be separated, the first normal form is satisfied.

For example: user user table, containing the field id,username,password

two。 The second paradigm

Building on the first paradigm, the goal is to ensure that each column in the table is related to the primary key.

If a relationship satisfies the first normal form and all columns except the primary key depend on the primary key, the second normal form is satisfied.

For example, a user has only one role, while one role corresponds to multiple users. The data table relationship can be established as follows to satisfy the second normal form.

User user table, field id,username,password,role_id

Role role table, field id,name

The user table associates the role table through role id (role_id)

3. The third paradigm

Building on the second paradigm, the goal is to ensure that the columns in the table are directly related to the primary key, not indirectly.

For example, a user can correspond to multiple roles, and a role can correspond to multiple users. The data table relationship can be established as follows to meet the third normal form.

User user table, field id,username,password

Role role table, field id,name

User_role user-role middle table, id,user_id,role_id

Like this, through the third table (intermediate table) to establish the relationship between the user table and the role table, while in line with the principle of paradigm, it can be called the third paradigm.

4. Anti-normalization

Anti-normalization refers to improving the read performance of the database by adding redundant or duplicated data.

For example, the user_role user-role middle table in the above example adds the field role_name.

De-normalization can reduce the number of join tables when associating queries.

Thank you for reading this article carefully. I hope the article "what are the three paradigms and anti-paradigms of database" shared by the editor will be helpful to everyone? at the same time, I also hope that you will support and pay attention to the industry information channel. more related knowledge is waiting for you to learn!

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