sql - Alter a MySQL column to be AUTO_INCREMENT

Question

I’m trying to modify a table to make its primary key column AUTO_INCREMENT after the fact. I have tried the following SQL, but got a syntax error notification.

ALTER TABLE document
ALTER COLUMN document_id AUTO_INCREMENT

Am I doing something wrong or is this not possible?

+--------------------+
| VERSION()          |
+--------------------+
| 5.0.75-0ubuntu10.2 |
+--------------------+

Answer 1

ALTER TABLE document MODIFY COLUMN document_id INT auto_increment