bigdir/db/migrate/20140703085204_clear_course_data.rb

class ClearCourseData < ActiveRecord::Migration
  def up
    # 清理课程表垃圾数据
    # 之前删除项目未删除课程的数据
    sql = 'delete from courses where name is null and extra not in (select identifier from projects)'
    execute(sql)
  end

  def down
  end
end