MVC Html辅助方法DropDownList的简单使用、连接MYSQL数据库用自定义model类接收

附上启发链接：https://www.cnblogs.com/CreateMyself/p/5424894.html

 [HttpGet]
        public ActionResult Edit(int id)
        {
            var db = Congfig.MySqlConn;
            const string sql = "SELECT S,W FROM SW";
            var result = db.ExecuteDataReader(sql);
            MySqlConnection con = new MySqlConnection("server=012.345.678.910;port=0123;User Id=UserId;password=Pwd;database=DB");
            MySqlDataAdapter da = new MySqlDataAdapter(sql, con);
            DataSet ds = new DataSet();
            da.Fill(ds);
            DataTable dt = ds.Tables[0];
            #region
            //从数据库中读取
            var categoryList = new List<BlogCategory>();
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                categoryList.Add(new BlogCategory() { CategoryId = dt.Rows[i][0].ToString(), CategoryName = dt.Rows[i][1].ToString() });
            }
            var selectItemList = new List<SelectListItem>()
            {
                //new SelectListItem(){Value="0",Text="全部",Selected=true}
            };
            var selectList = new SelectList(categoryList, "CategoryId", "CategoryName");
            selectItemList.AddRange(selectList);
            ViewBag.database = selectItemList;
            #endregion
            var model = Curd.GetModel<Users>(id);

            ViewBag.Msg = Msg;
            Msg = "";

            return View(model);
        }
        #region
        public class BlogCategory
        {
            public string CategoryId { get; set; }
            public string CategoryName { get; set; }
        }
        #endregion

 <div class="form-group marginB">
                    <label class="col-sm-1 control-label">设置管理区域</label>
                    <div class="col-sm-8">
                        @Html.DropDownList("database-dropdownlist", (ViewBag.database as IEnumerable<SelectListItem>)@*, new { @class = "btn btn-success dropdown-toggle form-control" }*@)
                    </div>
                </div>

效果图：