迁移实践课程的访问人数

db/migrate/20200106092135_modify_viewed_count_for_subjects.rb

@@ -0,0 +1,10 @@
+class ModifyViewedCountForSubjects < ActiveRecord::Migration[5.2]
+  def change
+
+    subjects = Subject.where(status: 2).includes(:shixuns)
+    subjects.find_each do |subject|
+      subject.update_attribute(:visits, subject.visits + subject.shixuns.pluck(:myshixuns_count).sum)
+    end
+
+  end
+end