Asynchronous command processing using the callback approach (C#) : SqlAsyncResult « ADO.net Database « ASP.NET Tutorial

<%@ Page Language="C#" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<%@ Import Namespace="System.Configuration" %>

<script runat="server">
    protected void Page_Load(object sender, EventArgs e)
    {
        SqlConnection DBCon;
        SqlCommand Command = new SqlCommand();
        SqlAsyncResult ASyncResult;

        DBCon = new SqlConnection();
        Command = new SqlCommand();
        DBCon.ConnectionString = ConfigurationManager.ConnectionStrings["DSN_NorthWind"].ConnectionString;

        Command.CommandText = 
                "SELECT TOP 5 Customers.CompanyName, Customers.ContactName, " +
                " Orders.OrderID, Orders.OrderDate, " +
                " Orders.RequiredDate, Orders.ShippedDate " +
                " FROM Orders, Customers " +
                " WHERE Orders.CustomerID = Customers.CustomerID " +
                " ORDER BY Customers.CompanyName, Customers.ContactName ";

        Command.CommandType = CommandType.Text;
        Command.Connection = DBCon;

        DBCon.Open();

        AsyncResult = Command.BeginExecuteReader(new AsyncCallback(CBMethod), 
                                        CommandBehavior.CloseConnection);
    }

    public void CBMethod(SQLAsyncResult ar)
    {
        SqlDataReader OrdersReader;

        OrdersReader = ar.EndExecuteReader(ar);

        gvOrders.DataSource = OrdersReader;
        gvOrders.DataBind();
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>The Call Back Approach</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <asp:GridView ID="gvOrders" Width="100%" AutoGenerateColumns="False"         
        Runat="server">
        <Columns>
        <asp:BoundField HeaderText="Company Name" 
            DataField="CompanyName"></asp:BoundField>
        <asp:BoundField HeaderText="Contact Name" 
            DataField="ContactName"></asp:BoundField>
        <asp:BoundField HeaderText="Order Date" DataField="orderdate" 
            DataFormatString="{0:d}"></asp:BoundField>
        <asp:BoundField HeaderText="Required Date" DataField="requireddate" 
            DataFormatString="{0:d}"></asp:BoundField>
        <asp:BoundField HeaderText="Shipped Date" DataField="shippeddate" 
            DataFormatString="{0:d}"></asp:BoundField>
        </Columns>
    </asp:GridView> 
    </div>
    </form>
</body>
</html>
File: Web.config

<configuration>

  <connectionStrings>
        <add name="DSN_Northwind" 
             connectionString="Data Source=localhost\SQLEXPRESS;Initial Catalog=Northwind;Integrated Security=True"
             providerName="System.Data.SqlClient" />

    </connectionStrings>

</configuration>
18.52.SqlAsyncResult
	18.52.1.	Asynchronous command processing using the callback approach (C#)
	18.52.2.	Asynchronous command processing using the callback approach (VB)