datatable 怎么只能插入一行吗？插入第二行就替代第一行了，不会累加插入。

前台

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="inproduct.aspx.cs" Inherits="inproduct" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
        <div>        
            <asp:Button ID="Button1" runat="server" Text="添加第一行" OnClick="Button1_Click" />
            <asp:Button ID="Button2" runat="server" Text="添加第二行" OnClick="Button2_Click" />
            <asp:GridView ID="GridView1" runat="server" EnableModelValidation="True">
            </asp:GridView>

        </div>
    </form>
</body>
</html>

后台程序

using System;
using System.Collections.Generic;
using System.Data;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class inproduct : System.Web.UI.Page
{

    public DataTable dt = new DataTable();
    protected void Page_Load(object sender, EventArgs e)
    {

        DataColumn dc1 = new DataColumn("prizename", Type.GetType("System.String"));
        DataColumn dc2 = new DataColumn("point", Type.GetType("System.Int16"));
        DataColumn dc3 = new DataColumn("number", Type.GetType("System.Int16"));
        DataColumn dc4 = new DataColumn("totalpoint", Type.GetType("System.Int64"));
        DataColumn dc5 = new DataColumn("prizeid", Type.GetType("System.String"));
        dt.Columns.Add(dc1);
        dt.Columns.Add(dc2);
        dt.Columns.Add(dc3);
        dt.Columns.Add(dc4);
        dt.Columns.Add(dc5);
        DataRow dr = dt.NewRow();
        dr["prizename"] = "娃娃1";
        dr["point"] = 10;
        dr["number"] = 1;
        dr["totalpoint"] = 10;
        dr["prizeid"] = "001";
        dt.Rows.Add(dr);
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }


    protected void Button1_Click(object sender, EventArgs e)
    {
        DataRow dr = dt.NewRow();
        dr["prizename"] = "娃娃2";
        dr["point"] = 20;
        dr["number"] = 2;
        dr["totalpoint"] = 20;
        dr["prizeid"] = "002";
        dt.Rows.Add(dr);
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }

    protected void Button2_Click(object sender, EventArgs e)
    {
        DataRow dr2 = dt.NewRow();
        dr2["prizename"] = "娃娃3";
        dr2["point"] = 30;
        dr2["number"] = 3;
        dr2["totalpoint"] = 30;
        dr2["prizeid"] = "003";
        dt.Rows.Add(dr2);

        GridView1.DataSource = dt;
        GridView1.DataBind();
    }
}

使用静态的表 首次加载定义列值
private static  DataTable dt = new DataTable(); //static 静态
private static int index = 0;
protected void Page_Load(object sender, EventArgs e)
{
    if(index == 0) //列名只在首次加载页面时添加
    {
        DataColumn dc1 = new DataColumn("prizename", Type.GetType("System.String"));
        DataColumn dc2 = new DataColumn("point", Type.GetType("System.Int16"));
        DataColumn dc3 = new DataColumn("number", Type.GetType("System.Int16"));
        DataColumn dc4 = new DataColumn("totalpoint", Type.GetType("System.Int64"));
        DataColumn dc5 = new DataColumn("prizeid", Type.GetType("System.String"));
        index += 1;
    }      
 
}