How to rollback just one step using rake db:migrate - ruby-on-rails

Question

After adding migration files in the db/migrate folder and running rake db:migrate, I want get back to the previous step, I think using VERSION=n is the right way to do that, but I don't know the correct value of n to use. Is there any command to check the current n value?
It would be great if anyone could provide full instructions on how to use rake db:migrate.

Answer 1

For starters
rake db:rollback will get you back one step
then
rake db:rollback STEP=n
Will roll you back n migrations where n is the number of recent migrations you want to rollback.
More references here.

Answer 2

Roll back the most recent migration:
rake db:rollback
Roll back the n most recent migrations:
rake db:rollback STEP=n
You can find full instructions on the use of Rails migration tasks for rake on the Rails Guide for running migrations.
Here's some more:
rake db:migrate - Run all migrations that haven't been run already
rake db:migrate VERSION=20080906120000 - Run all necessary migrations (up or down) to get to the given version
rake db:migrate RAILS_ENV=test - Run migrations in the given environment
rake db:migrate:redo - Roll back one migration and run it again
rake db:migrate:redo STEP=n - Roll back the last n migrations and run them again
rake db:migrate:up VERSION=20080906120000 - Run the up method for the given migration
rake db:migrate:down VERSION=20080906120000 - Run the down method for the given migration
And to answer your question about where you get a migration's version number from:
The version is the numerical prefix on the migration's filename. For
example, to migrate to version 20080906120000 run
$ rake db:migrate VERSION=20080906120000
(From Running Migrations in the Rails Guides)

Answer 3

Best way is running Particular migration again by using down or up(in rails 4. It's change)
rails db:migrate:up VERSION=timestamp
Now how you get the timestamp.
Go to this path
/db/migrate
Identify migration file you want to revert.pick the timestamp from that file name.

Answer 4

If the version is 20150616132425, then use:
rails db:migrate:down VERSION=20150616132425

Answer 5

Other people have already answered you how to rollback, but you also asked how you could identify the version number of a migration.
rake db:migrate:status gives a list of your migrations version, name and status (up or down)
Your can also find the migration file, which contain a timestamp in the filename, that is the version number. Migrations are located in folder: /db/migrate

Answer 6

try {
$result=DB::table('users')->whereExists(function ($Query){
$Query->where('id','<','14162756');
$Query->whereBetween('password',[14162756,48384486]);
$Query->whereIn('id',[3,8,12]);
});
}catch (\Exception $error){
Log::error($error);
DB::rollBack(1);
return redirect()->route('bye');
}