migrate修改

db/migrate/20190820102040_change_exercise_1930_position.rb

@@ -3,7 +3,7 @@ class ChangeExercise1930Position < ActiveRecord::Migration[5.2]
     exs = Exercise.all.includes(:exercise_questions)
     exs.each do |ex|
       ex_questions = ex&.exercise_questions&.select(:id,:question_number,:exercise_id)&.order("question_number ASC")  #试卷的位置迁移
-      if ex_questions.exists?
+      if ex_questions.present?
         ex_questions.each_with_index do |q,index|
           puts index
           q_num = index + 1
@@ -14,7 +14,7 @@ class ChangeExercise1930Position < ActiveRecord::Migration[5.2]
       end
 
       ex_q_bank = ex&.exercise_bank&.exercise_bank_questions&.select(:id,:question_number,:exercise_bank_id,:shixun_id)&.order("question_number ASC") #试卷的习题库位置迁移
-      if ex_q_bank.exists?
+      if ex_q_bank.present?
         ex_q_bank.each_with_index do |q,index|
           puts index
           q_num_1 = index + 1