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Editor to share with you the role of the mysql primary key, I believe that most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to understand it!

What is the primary key?

A database primary key refers to a combination of columns or columns whose value uniquely identifies each row in the table, through which the physical integrity of the table can be enforced. The primary key is mainly used to associate foreign keys with other tables, as well as to modify and delete this record.

The primary key (primary key) is a column (or set of columns) whose value uniquely distinguishes each row in the table.

This column (or set of columns) that uniquely identifies each row in the table is called the primary key. Without a primary key, it is difficult to update or delete specific rows in the table because there is no safe way to guarantee that only the relevant rows are designed.

Although primary keys are not always required, most database designers should ensure that each table they create has a primary key for future data manipulation and management

Any column in the table can be used as a primary key, as long as it meets the following conditions:

1. No two rows have the same primary key value

2. Each row must have a primary key value (null values are not allowed in the primary key column)

What is the use of the primary key?

The primary key is the unique identification that can determine a record, which is mainly used to determine the uniqueness of the data. The primary key field must be unique, must be non-empty, there can be only one primary key in a table, and the primary key can contain one or more fields.

For example, a record includes identity plus sign, name, age, school, nationality, gender, etc. The ID number is the only one that can identify you, and everything else may be duplicated, so the ID number is the primary key.

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