class ModifyCourseGroupForCourses < ActiveRecord::Migration[5.2]
  def change
    groups = CourseGroup.where(course_id:3429).order("created_at desc").group(:name)
    ActiveRecord::Base.transaction do
      groups.each do |g|
        CourseGroup.where(name: g.name).where.not(id: g.id).each do |cg|
          cg.course_members.each do |cm|
            cm.update_attributes!(course_group_id: g.id)
          end
          cg.exercise_group_settings.update_all(course_group_id: g.id)
          cg.attachment_group_settings.update_all(course_group_id: g.id)
          cg.homework_group_reviews.update_all(course_group_id: g.id)
          cg.homework_group_settings.update_all(course_group_id: g.id)
          cg.teacher_course_groups.update_all(course_group_id: g.id)
          cg.destroy!
        end
      end
    end
  end
end