@mcki0127 if you’re still developing the application, and it’s only on your own computer, you could rollback all the migrations (yii migrate/down) until you rollback the migration you want to modify, modify it, then play the migrations again.
BUT, there is absolutely no benefits in doing that, you’ll be just wasting some of your time. And if you’re working in a team, or the application is already deployed, this will surely provoque a mess.
On the contrary, you’ll be defeating the purpose of migrations by doing that, that is: migrations represent changes to your data structure which happened during time. By modifying an existing migration, you’re “cheating” history.
Just create a new migration and make the desired changes in it, run it, and be done with it.
Some user recently reported on slack that he has more than 200 migrations, and this is perfectly fine. They do not impact your website performances. (slack thread)