fix bug

app/controllers/exercises_controller.rb

@@ -1173,7 +1173,6 @@ class ExercisesController < ApplicationController
     ActiveRecord::Base.transaction do
       begin
         @current_user_id = current_user.id
-        @exercise = @exercise.joins(:exercise_questions,:exercise_users)
         exercise_ids = [@exercise.id]
         @exercise_status = @exercise.get_exercise_status(current_user.id)
         @course_all_members = @course.students
@@ -1302,7 +1301,7 @@ class ExercisesController < ApplicationController
                   normal_status(-1,"暂无用户提交")
                 else
                   @exercise = @exercise.includes(:exercise_questions)
-                  @export_ex_users = @export_ex_users.joins(user: :user_extension)
+                  @export_ex_users = @export_ex_users.includes(user: :user_extension)
                   get_export_users(@exercise,@course,@export_ex_users)
                   exercise_export_name =
                       "#{current_user.real_name}_#{@course.name}_#{@exercise.exercise_name}_#{Time.now.strftime('%Y%m%d_%H%M%S')}"