SalesIdSl = new SelectList(PublicFunc.GetAllSales(RootOrgId, currentUserName, currentUserId), "Id", "Name");

 SysTypeList = WebHelper.ToSelectList<SysType>(true);

 public static SelectList ToSelectList<TEnum>(bool useEnumValue = true, object defaultItem = null) where TEnum : struct
        {
            List<object> items = EnumHelper.GetEnumList<TEnum>(useEnumValue);
            if (defaultItem != null)
            {//dreams add 20170206 增加枚举类型之外选项，用于增加“全部”
                items.Insert(0, defaultItem);
            }


            return new SelectList(items, "Value", "Text");
        }

 @Html.DropDownListFor(m => m.StudentId, Model.StudentIdSL, new { @class = "form-control", @id = "StudentID" })

 @Html.DropDownList("SubType", Model.SubTypeShowList, new { @class = "form-control", @id = "SubType" })