关于asp:DropDownList控件的问题
lstCategory是绑定到数据库表Categories，HTML显示如下代码：
<select name= "lstCategory " id= "lstCategory " style= "width:80px;Z-INDEX: 102; LEFT: 16px; POSITION:

absolute; TOP: 376px ">
<option selected= "selected " value= "1 "> Beverages </option>
<option value= "2 "> Condiments </option>
<option value= "3 "> Confections </option>
<option value= "4 "> Dairy Products </option>
<option value= "5 "> Grains/Cereals </option>
<option value= "6 "> Meat/Poultry </option>
<option value= "7 "> Produce </option>
<option value= "8 "> Seafood </option>

</select>
我能否在lstCategory中增加一项自定义的（前提事数据库的表不需要增加数据行）：

<option value= "0 "> All </option>


ASP.NET页：

CodeWizard.aspx
---------------------------
<asp:DropDownList id= "lstCategory " style= "Z-INDEX: 102; LEFT: 16px; POSITION: absolute; TOP: 376px "
runat= "server " Width= "80px "> </asp:DropDownList>

CodeWizard.aspx.cs
----------------------------
private void Page_Load(object sender, System.EventArgs e)
{
// 在此处放置用户代码以初始化页面
if (!Page.IsPostBack)
{
DataGrid1.DataSource = GetProductsDataSet(0);
DataGrid1.DataBind();
}

if (!Page.IsPostBack)
{
Response.Write (Page.IsPostBack);
lstCategory.DataSource=GetCategories();
lstCategory.DataTextField= "CategoryName ";
lstCategory.DataValueField= "CategoryID ";
lstCategory.DataBind();
}

}

[解决办法]
lstCategory.DataBind();
lstCategory.Items.InsertAt(0,new ItemList( "xx ", "xx "));
[解决办法]
if (!Page.IsPostBack)
{
Response.Write (Page.IsPostBack);
lstCategory.DataSource=GetCategories();
lstCategory.DataTextField= "CategoryName ";
lstCategory.DataValueField= "CategoryID ";
lstCategory.DataBind();
ListItem li = new ListItem();
li.Value = "0 ";
li.Text = "all ";
lstCategory.Items.Insert(0,li);
}

[解决办法]
可以考虑动态添加item。
[解决办法]
if (!Page.IsPostBack)
{
Response.Write (Page.IsPostBack);
lstCategory.DataSource=GetCategories();
lstCategory.DataTextField= "CategoryName ";
lstCategory.DataValueField= "CategoryID ";
lstCategory.DataBind();
lstCategory.Items.InsertAt(0,new ItemList( "All ", "0 "));

}
[解决办法]
...都说光了。
[解决办法]
先绑定好，之后加上
this.DropDownList1.Items.Insert(0,new ListItem( " ", " "));