实训迁移

db/migrate/20190622055449_modify_shixun_info_for_shixuns.rb

@@ -1,4 +1,4 @@
-class ModifyScriptAndDescriptionForShixuninfo < ActiveRecord::Migration[5.2]
+class ModifyShixunInfoForShixuns < ActiveRecord::Migration[5.2]
   def change
     Shixun.find_each do |shixun|
       if shixun.shixun_info
@@ -11,6 +11,8 @@ class ModifyScriptAndDescriptionForShixuninfo < ActiveRecord::Migration[5.2]
                            evaluate_script: shixun[:evaluate_script], shixun_id: shixun.id)
       end
     end
+    if shixun.description.present?
       remove_columns :shixuns, :description, :propaedeutics, :evaluate_script
     end
   end
+end