How to Automatically Add an Auto-Increment Primary Key to an Existing Database Table?

Automatically Inserting Auto-Increment Primary Key and Values into Existing Table

Encountering tables without primary keys or auto-increment columns is a common scenario in database management. To add a primary key column and assign unique identifiers to existing rows, a specific approach is required.

To achieve this, executing an ALTER TABLE statement with the desired column specifications is recommended. For instance, the following statement adds an auto-increment primary key column named "id" to an existing table:

ALTER TABLE tbl ADD id INT PRIMARY KEY AUTO_INCREMENT;

Upon execution, this statement creates the "id" column and automatically populates it with auto-increment values for each row in the table, starting with 1. This effectively adds a unique identifier to each row without the need for manual intervention.

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