gridview定义的dropdownlist控件怎么绑定到字段<asp:GridView ID="GridView1" runat="server" AllowPaging="True" DataKeyNames="roomno" OnRowEditing="GridView1_RowEditing"  OnRowCancelingEdit="GridView1_RowCancelingEdit" OnRowDeleting="GridView1_RowDeleting" OnRowUpdating="GridView1_RowUpdating" AutoGenerateColumns="False" >
            <Columns>
                <asp:BoundField HeaderText="房间号" DataField="roomno"  />
                <asp:TemplateField HeaderText="房间类型" >        <%--//如何绑定到字段--%>
               <ItemTemplate>
                <asp:DropDownList ID="roomtype" runat="server"  >
                <asp:ListItem  Value="1">豪华房</asp:ListItem>
                  <asp:ListItem  Value="2">商务房</asp:ListItem>
                  <asp:ListItem  Value="3">双人房</asp:ListItem>
                  <asp:ListItem  Value="4">房型4</asp:ListItem>
                  <asp:ListItem  Value="5">房型5</asp:ListItem>
                  <asp:ListItem  Value="6">房型6</asp:ListItem>
                </asp:DropDownList>
                </ItemTemplate>
                </asp:TemplateField>
                <asp:BoundField DataField="roomstatu" HeaderText="房间状态" />
                <asp:BoundField HeaderText="房价" DataField="unitprice" DataFormatString="{0:c}" />
                <asp:CommandField HeaderText="编辑" ShowEditButton="True" />
                <asp:CommandField HeaderText="删除" ShowDeleteButton="True" />
            </Columns>
        </asp:GridView>.cs
 protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {
        try
        {
            int index = e.RowIndex;//当前选择行索引值
           string roomno = GridView1.DataKeys[index].Value.ToString();//获取主键房间号
           string roomtype = ((TextBox)(GridView1.Rows[index].Cells[1].Controls[0])).Text.Trim();
           string roomstatu = ((TextBox)(GridView1.Rows[index].Cells[2].Controls[0])).Text.Trim();
           string unitprice = ((TextBox)(GridView1.Rows[index].Cells[3].Controls[0])).Text.Trim();           string sql = "update room set roomtype="+roomtype+",roomstatu="+roomstatu+",unitprice="+unitprice+"";//更新语句
           SqlConnection conn = new SqlConnection(strCon);
           conn.Open();
           SqlCommand comm = new SqlCommand(sql, conn);
           int ret = comm.ExecuteNonQuery();
            if (ret>0)
            {
                //更新成功
            }
            else
            {
                //更新失败
            }
            GridView1.EditIndex = -1;
            DataBind();
        }
        catch (Exception ex)
        { 
        throw;
        }
    }
 
    protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {
        int index = e.RowIndex;
        string roomno = GridView1.DataKeys[index].Value.ToString();
        string sql = "delete from room where roomno="+roomno+"";//删除语句
        SqlConnection conn = new SqlConnection(strCon);
        conn.Open();
        SqlCommand comm = new SqlCommand(sql, conn);
        conn.Close();
        DataBind();
    }