一，在控制器中写好数据绑定          

//通过ID查找出整列的数据

            Case.Models.Case theCase = db.Case.Find(id);

            ViewBag.CaseUser2 = theCase;

二，在视图中

实例化一个变量

@{

    ViewBag.Title = "Edit";

    var thecase = ViewBag.CaseUser2 as Case.Models.Case;

}

三，则可以用ViewBag将里面的每一列数据选出来判断

        @if (thecase.CaseUser2 == "" )

        {

            <div class="form-group">

                @Html.LabelFor(model => model.CaseUser2, new { @class = "control-label col-md-2", style = "padding-top: 6px;" })

                <div class="col-md-10">

                    @Html.DropDownList("CaseUser2", (SelectList)ViewData["CaseUserList2"], new { @class = "selectpicker", @data_style = "btn-default" })

                    @Html.ValidationMessageFor(model => model.CaseUser2)

                </div>

            </div>

        }