class MergeTwoHomeworks < ActiveRecord::Migration
  def up
    student_works = StudentWork.where("homework_common_id = 3387 and user_id in (11256, 11259, 11252, 11499)")
    unless student_works.nil?
      student_works.each do |work|
        work.update_column('homework_common_id', 3463)
      end
    end
    homework = HomeworkCommon.find 3387
    homework.destroy if homework
    stu_works = StudentWork.where("homework_common_id = 3387")
    stu_work_ids = stu_works.empty? ? "(-1)" : "(" + stu_works.map{|work| work.id}.join(',') + ")"
    stu_work_tests = StudentWorkTest.where("student_work_id in #{stu_work_ids}")
    stu_work_tests.destroy_all if stu_work_tests
    stu_works.destroy_all if stu_works
  end

  def down
  end
end