mysql add an autoincrement column with start value

Question

I would like to add a new autoincrement column to a pre-existing table. However, I need the ids that are in that column to start at a particular value, ie

alter table MyTable 
add column MyColumn int unsigned not null primary key auto_increment=999999;

Is this possible? I tried issuing:

alter table MyTable auto_increment=999999;

before I added the column, but it had no effect. Because adding the column will automatically generate the ids, it is not sufficient to run the second statement after the first.

Answer 1

No, it works to add an AI column with a starting position. But you almost got the syntax right. Here's a demo:

mysql> CREATE TABLE foo (v varchar(10));

mysql> INSERT INTO foo VALUES ('one'), ('two'), ('three');

Then comes the tricky syntax. You have to declare the column as AUTO_INCREMENT, but then also give the table option for the AUTO_INCREMENT starting value. And you need a comma to separate the ADD COLUMN from the table option.

mysql> ALTER TABLE foo ADD COLUMN id INT AUTO_INCREMENT PRIMARY KEY,
    AUTO_INCREMENT=999999;

mysql> select * from foo;
+-------+---------+
| v     | id      |
+-------+---------+
| one   |  999999 |
| two   | 1000000 |
| three | 1000001 |
+-------+---------+