diff --git a/app/models/gtopic_bank.rb b/app/models/gtopic_bank.rb
index af5b267a6..609219711 100644
--- a/app/models/gtopic_bank.rb
+++ b/app/models/gtopic_bank.rb
@@ -1,7 +1,7 @@
 class GtopicBank < ApplicationRecord
   belongs_to :user
-  belongs_to :graduation_topic
-  belongs_to :course_list
+  belongs_to :graduation_topic, optional: true
+  belongs_to :course_list, optional: true
 
   has_many :attachments, as: :container, dependent: :destroy
   has_many :graduation_topics, dependent: :nullify
diff --git a/db/migrate/20190907021100_migrate_bank_reference_id.rb b/db/migrate/20190907021100_migrate_bank_reference_id.rb
new file mode 100644
index 000000000..c71034167
--- /dev/null
+++ b/db/migrate/20190907021100_migrate_bank_reference_id.rb
@@ -0,0 +1,31 @@
+class MigrateBankReferenceId < ActiveRecord::Migration[5.2]
+  def change
+    HomeworkBank.all.each do |bank|
+      if bank.homework_common
+        bank.homework_common.update_column("homework_bank_id", bank.id) if bank.homework_common.homework_bank_id.nil?
+      end
+    end
+
+    GtopicBank.all.each do |bank|
+      if bank.graduation_topic
+        bank.graduation_topic.update_column("gtopic_bank_id", bank.id) if bank.graduation_topic.gtopic_bank_id.nil?
+      end
+    end
+
+    GtaskBank.all.each do |bank|
+      if bank.graduation_task
+        bank.graduation_task.update_column("gtask_bank_id", bank.id) if bank.graduation_task.gtask_bank_id.nil?
+      end
+    end
+
+    ExerciseBank.all.each do |bank|
+      if bank.container_type == 'Exercise'
+        exercise = Exercise.find_by(id: bank.container_id)
+        exercise.update_column("exercise_bank_id", bank.id) if exercise && exercise.exercise_bank_id.nil?
+      elsif bank.container_type == 'Poll'
+        poll = Poll.find_by(id: bank.container_id)
+        poll.update_column("exercise_bank_id", bank.id) if poll && poll.exercise_bank_id.nil?
+      end
+    end
+  end
+end