加载数据库User表中创建人，显示到界面控件中，其中数据库定义是int 型 外键（User表）

if (BaseClass.UserCache.ContainsKey(userInfo.CreatedBy ?? -1))

                    {

 

                        txtCreateBy.Text = BaseClass.UserCache[userInfo.CreatedBy ?? -1];

                    }

                    else txtCreateBy.Text = "error";

PublicBase.cs类

        /// <summary>

        /// 用户名缓存:key=UserId value=DisPlayName

        /// </summary>

        public static Dictionary<int, string> UserCache = new Dictionary<int, string>();

UserMessage类：public int? CreatedBy { get; set; }