C# 如何从下拉列表选择更改文本框中的数据显示？

大家好，作为我发布的主题。我真的需要知道，如何从DDL中得到可以自动改变文本框显示的结果。我们的每件商品都有不止一个尺码，有时当您点击不同尺码时，价格会有所不同。如何实现此功能

如果有任何帮助，我将不胜感激

以下是我的示例代码：

详细信息。aspx:

<asp:TemplateField SortExpression="Size" ItemStyle-Wrap="True" ItemStyle-HorizontalAlign="Left" ItemStyle-VerticalAlign="Bottom" HeaderStyle-Wrap="False" HeaderText="Options">
  <ItemTemplate>
    Size:<asp:DropDownList ID="DropDownList1" runat="server" DataSourceID="SizeSource" AutoPostBack="true" DataTextField="Size" DataValueField="Size" Height="22px" Width="60px">
    </asp:DropDownList>
    &nbsp;&nbsp;&nbsp;&nbsp; Qty:<asp:TextBox ID="TextBox2" runat="server" Height="16px" Width="30px" Text="<%# 1 %>"></asp:TextBox>
    <br />
    Price(USD):
    <asp:TextBox runat="server" DataSourceID="SizeSource" SortExpression="Price" DataFormatString="{0}" ID="PriceList" Width="50px" Height="16px" ValidationGroup="Price" AutoPostBack="True" />
    <asp:SqlDataSource ID="SizeSource" runat="server" ConnectionString="<%$ ConnectionStrings:LIFEbabySAP %>" SelectCommand="SELECT left(T0.ItemCode,8) as Image, left(T0.ItemCode,8) as Code, T0.U_ItemName as Name, T0.U_Size as Size, T0.U_Colour as Color,case T1.Onhand when 0 then 'Out of Stock' else 'In Stock' end as Availability, T0.UserText as Description, CAST(T2.Price as Int)as Price FROM OITM T0 inner join oitw T1 on T0.ItemCode = T1.Itemcode inner join itm1 T2 on T0.ItemCode = T2.ItemCode WHERE (left(T0.ItemCode,8) = @Image) and T0.U_USE  = 'Y' and T1.Onhand != 0 and T1.whscode ='BAW' and T2.PriceList = 10">
      <SelectParameters>
        <asp:QueryStringParameter Name="Image" QueryStringField="product" Type="String" />
      </SelectParameters>
    </asp:SqlDataSource>
  </ItemTemplate>
  <HeaderStyle Wrap="False"></HeaderStyle>
  <ItemStyle HorizontalAlign="Left" VerticalAlign="Bottom" Wrap="True"></ItemStyle>
</asp:TemplateField>

private void Page_Load(object sender, System.EventArgs e)
{
  if (!IsPostBack)
  {
    string Size = Request.QueryString["Price"];
    if (Size != null)
    {
      ddlCategory.SelectedValue = Size;
    }
  }

  ItemsGet();

}

protected void CatalogList_SelectedIndexChanged(object sender, EventArgs e)
{
  string Image = CatalogList.SelectedValue.ToString().Trim();
  string catid = ddlCategory.SelectedValue;
  Response.Redirect("Details.aspx?product="
    + Image
    + "&Price="
    + catid);
}

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您能再指定一点吗？您想获取下拉值并将其放入文本框中吗？这是否将在服务器控件中（即gridview、datalist等…）