怎么通过button 来更改Lable的值
C# code<asp:GridView ID="gvSelect" runat="server" AutoGenerateColumns="False" DataKeyNames="Pro_Id" onrowdeleting="gvSelect_RowDeleting" onrowdatabound="gvSelect_RowDataBound" BackColor="LightGoldenrodYellow" BorderColor="Tan" BorderWidth="1px" CellPadding="2" ForeColor="Black" GridLines="None" Width="1000px" AllowPaging="True" AllowSorting="True" ClientIDMode="Static" PageIndex="0" PageSize="5" onpageindexchanging="gvSelect_PageIndexChanging" onrowediting="gvSelect_RowEditing" onrowcreated="gvSelect_RowCreated" onrowcommand="gvSelect_RowCommand" > <AlternatingRowStyle BackColor="PaleGoldenrod" /> <Columns> <asp:TemplateField HeaderText="图片"> <ItemTemplate> <img src='img/<%# Eval("Pro_Image") %>' width="50" height="50" alt="" /> </ItemTemplate> </asp:TemplateField> <asp:BoundField DataField="Pro_Name" HeaderText="名称" SortExpression="Pro_Name" /> <asp:BoundField DataField="Pro_Price" HeaderText="价格" SortExpression="Pro_Price" DataFormatString="{0:f2}"/> <asp:TemplateField HeaderText="数量"> <ItemTemplate> <asp:Button ID="jian" CommandArgument='<%# Eval("Pro_Id") %>' CommandName="jian" runat="server" Text="-" /> <asp:Label ID="Num" runat="server" Text="1"></asp:Label> <asp:Button ID="jia" CommandArgument='<%# Eval("Pro_Id") %>' CommandName="jia" runat="server" Text="+" /> </ItemTemplate> </asp:TemplateField> <asp:CommandField ShowDeleteButton="True" DeleteText="取消" HeaderText="取消" /> </Columns> <FooterStyle BackColor="Tan" /> <HeaderStyle BackColor="Tan" Font-Bold="True" /> <PagerStyle BackColor="PaleGoldenrod" ForeColor="DarkSlateBlue" HorizontalAlign="Center" /> <SelectedRowStyle BackColor="DarkSlateBlue" ForeColor="GhostWhite" /> <SortedAscendingCellStyle BackColor="#FAFAE7" /> <SortedAscendingHeaderStyle BackColor="#DAC09E" /> <SortedDescendingCellStyle BackColor="#EDA612" /> <SortedDescendingHeaderStyle BackColor="#EDA612" /> </asp:GridView>