You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: 20151006200453_remove_columns_discipline_id_knowledge_area_id_and_classes_from_lesson_plans.rb
    path of file: ./repos/i-diario/db/migrate
    
    the code of the file until where you have to start completion: class RemoveColumnsDisciplineIdKnowledgeAreaIdAndClassesFromLessonPlans < ActiveRecord::Migration[4.2]
  def chang
    
  def change
    execute <<-SQL
      INSERT INTO discipline_lesson_plans(lesson_plan_id, discipline_id, classes)
      SELECT id, discipline_id, classes FROM lesson_plans WHERE discipline_id IS NOT NULL ORDER BY id;

      INSERT INTO knowledge_area_lesson_plans(lesson_plan_id)
      SELECT id FROM lesson_plans WHERE discipline_id IS NULL ORDER BY id;
    SQL

    remove_column :lesson_plans, :discipline_id
    remove_column :lesson_plans, :knowledge_area_id
    remove_column :lesson_plans, :classes
  end