undo migration rails code example

Example 1: rails rollback multiple migrations

rake db:rollback STEP=n 
# n = how many migrations you want to rollback

Example 2: rails revert migration

rake db:rollback

Example 3: rials db down

bin/rails db:migrate:down VERSION=YYYYMMDDHHMMSS

Example 4: rails redo last migration

rake db:migrate:redo STEP=n