Migration Commands

ruby script/generate migration migration_name table_name:table_properties
rake db:migrate
rake db:migrate VERSION=20090303032709 #back to specific version
rake db:migrate:down VERSION=20090303032709
rake db:migrate:up VERSION=20090303032712 #up to specific version
rake db:migrate:redo STEP=3 #rollback and migrating back again
rake db:rollback
rake db:rollback STEP=3 #number of step backward
rake db:reset #drop the table

http://guides.rails.info/migrations.html