在按钮单击事件上显示购物车详细信息

Question

我想在cart上显示Button_Click_Event个详细信息。我正在使用ASP.NET框架的Gridview控件。但是会发生以下异常：

object reference is not set to a instance of an object.

我该如何解决？这是我的代码：

protected void ImageButton1_Click(object sender, ImageClickEventArgs e)
{
    string st = "select * FROM cart_master";
    cmd = new SqlCommand(st, sqlcon);
    cmd.Connection.Open();
    cmd.ExecuteNonQuery();
    SqlDataAdapter sda = new SqlDataAdapter(cmd);
    DataSet ds = new DataSet();
    GridView GridView1 = (GridView)ContentPlaceHolder1.FindControl("GridView1");
    sda.Fill(ds, "cart_master");
    GridView1.DataSource = ds.Tables["cart_master"];
    GridView1.DataBind();
    cmd.Connection.Close();
}

Answer 1

而不是数据集，只需从适配器填充数据表

DataTable dataTable = new DataTable("ResultDataTable");
sda.Fill( dataTable);
GridView1.DataSource = dataTable;