asp.net中关于dropdwonlist无法获得值问题

复制代码 代码如下:

<label>发布栏目：<asp:DropDownList runat="server"></asp:DropDownList></label

复制代码 代码如下:

SourceDb DropDwonListData = new SourceDb();
string DropDwonSelect = "SELECT * FROM [Section]";
sectionDropDownList.DataSource = DropDwonListData.DatasetDb(DropDwonSelect).Tables[0].DefaultView;
sectionDropDownList.DataTextField = "name";
sectionDropDownList.DataValueField = "code";
sectionDropDownList.DataBind();

复制代码 代码如下:

string newsTitle = sectionDropDownList.SelectedValue;
Response.Write(newsTitle);

复制代码 代码如下:

<label>发布栏目：<asp:DropDownList runat="server"></asp:DropDownList></label

复制代码 代码如下:

if(!IsPostBack){
　　SourceDb DropDwonListData
= new SourceDb();
　　string DropDwonSelect = "SELECT * FROM [Section]";
　　sectionDropDownList.DataSource = DropDwonListData.DatasetDb(DropDwonSelect).Tables[0].DefaultView;
　　sectionDropDownList.DataTextField = "name";
　　sectionDropDownList.DataValueField = "code";
　　sectionDropDownList.DataBind();
}

复制代码 代码如下:

string newsTitle = sectionDropDownList.SelectedValue;
Response.Write(newsTitle);