public void QueryCourse(string filter, int flag)
 {
     if (flag == 2 || flag == 4)
     {
         Console.WriteLine("无权限");
         return;
     }
     MysqlClient.Query(flag, filter);
 }
 public void QueryCourse(string filter, int flag)
 {
     MysqlClient.Query(flag, filter);
 }