Sequel migration rake tasks based on https://gist.github.com/1409152

sequel_migrations.rake

namespace :db do
  require 'sequel'
  namespace :migrate do
    Sequel.extension :migration

    task :connect do
      if ENV['DATABASE_URL']
        DB = Sequel.connect(ENV['DATABASE_URL'])
      else
        puts 'ABORTING: You must set the DATABASE_URL environment variable!'
        exit false
      end
    end

    desc 'Perform migration reset (full erase and migration up).'
    task :reset => [:connect] do
      Sequel::Migrator.run(DB, 'migrations', :target => 0)
      Sequel::Migrator.run(DB, 'migrations')
      puts '*** db:migrate:reset executed ***'
    end

    desc 'Perform migration up/down to VERSION.'
    task :to => [:connect] do
      version = ENV['VERSION'].to_i
      if version == 0
        puts 'VERSION must be larger than 0. Use rake db:migrate:down to erase all data.'
        exit false
      end

      Sequel::Migrator.run(DB, 'migrations', :target => version)
      puts "*** db:migrate:to VERSION=[#{version}] executed ***"
    end

    desc 'Perform migration up to latest migration available.'
    task :up => [:connect] do
      Sequel::Migrator.run(DB, 'migrations')
      puts '*** db:migrate:up executed ***'
    end

    desc 'Perform migration down (erase all data).'
    task :down => [:connect] do
      Sequel::Migrator.run(DB, 'migrations', :target => 0)
      puts '*** db:migrate:down executed ***'
    end
  end
end