How to Correctly Add AUTO_INCREMENT to an Existing MySQL Column?

Adding AUTO_INCREMENT to an Existing MySQL Column

Database administrators sometimes need to add auto-increment functionality to an existing primary key column. A common mistake is using incorrect SQL syntax. For instance, the following command will result in a syntax error:

<code class="language-sql">ALTER TABLE document
ALTER COLUMN document_id AUTO_INCREMENT;</code>

The correct syntax to modify the column and enable auto-increment is:

<code class="language-sql">ALTER TABLE document MODIFY COLUMN document_id INT auto_increment;</code>

This updated command explicitly specifies the data type (INT) for the document_id column, ensuring the auto_increment attribute is applied correctly. This avoids syntax errors and properly configures the column for automatic incrementing values.

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