diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
index 4cb838b8c..009d5c4d6 100644
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -575,7 +575,7 @@ class UsersController < ApplicationController
     end
     if !params[:search].nil?
       search = "%#{params[:search].to_s.strip.downcase}%"
-      @course = @user.courses.where("is_delete = 0 and #{Course.table_name}.id != #{homework.course_id} and #{Course.table_name}.id = #{params[:search].to_i } or #{Course.table_name}.name like :p",:p=>search).select { |course|  @user.allowed_to?(:as_teacher,course)}
+      @course = @user.courses.where("is_delete = 0 and #{Course.table_name}.id != #{homework.course_id} and (#{Course.table_name}.id = #{params[:search].to_i } or #{Course.table_name}.name like :p)",:p=>search).select { |course|  @user.allowed_to?(:as_teacher,course)}
     else
       @course = @user.courses.where("is_delete = 0 and #{Course.table_name}.id != #{homework.course_id}").select { |course|  @user.allowed_to?(:as_teacher,course)}
     end