将MySQL栏变更为AUTO_INCREMENT时发生错误

Question

Here is my current table design:

I have several columns and no KEYs set, so when I try the following command:

ALTER TABLE users MODIFY COLUMN id INT auto_increment;

it gives me an error. I want the id column in the table to auto-increment and I want it to start with 1.

Answer 1

I think you are missing the primary key definition. Try this:

ALTER TABLE users MODIFY id INT AUTO_INCREMENT PRIMARY KEY

Also, I recommend you check this out.

Answer 2

您必须使用AUTO_INCREMENT指定PRIMARY_KEY ：

ALTER TABLE users MODIFY id INT PRIMARY_KEY AUTO_INCREMENT;