OleCommand and OleParameter : OleCommand « ADO.net Database « ASP.NET Tutorial

<%@ Page Language="C#" %>
<%@ import Namespace="System.Data" %>
<%@ import Namespace="System.Data.OleDb" %>
<script runat="server">

    void Page_Load(object sender, EventArgs e) {
        if (!Page.IsPostBack)
        {
            OleDbConnection myConnection = new OleDbConnection("PROVIDER=Microsoft.Jet.OLEDB.4.0;DATA SOURCE="+ Server.MapPath("EmployeeDatabase.mdb;"));
    
            try{
                string CommandTextPublisher = "SELECT ID, FirstName FROM Employee";
                OleDbCommand myCommandPublishers = new OleDbCommand(CommandTextPublisher, myConnection);
    
                myConnection.Open();
    
                DropDownList1.DataSource = myCommandPublishers.ExecuteReader();
                DropDownList1.DataTextField = "FirstName";
                DropDownList1.DataValueField = "ID";
                DropDownList1.DataBind();
                DropDownList1.Items.Insert(0, new ListItem("-- All Publishers --", "0"));
            }
            catch (Exception ex){
                throw(ex);
            }
            finally{
                myConnection.Close();
            }
        }
    }
    
    void ApplyFilter_Click(Object sender, EventArgs e) {
        OleDbConnection myConnection = new OleDbConnection("PROVIDER=Microsoft.Jet.OLEDB.4.0;DATA SOURCE="+ Server.MapPath("EmployeeDatabase.mdb;"));
    
        try{
            string CommandTextBooks = "SELECT Book.BookTitle, Publisher.PublisherName FROM Book INNER JOIN Publisher on Book.BookPublisherID = Publisher.PublisherID WHERE ?=0 OR Book.BookPublisherID=? ORDER BY Book.BookTitle";
            OleDbCommand myCommandBooks = new OleDbCommand(CommandTextBooks, myConnection);
    
            OleDbParameter myParameter1 = new OleDbParameter();
            myParameter1.ParameterName = "@pub1";
            myParameter1.OleDbType = OleDbType.Integer;
            myParameter1.Value = DropDownList1.SelectedValue;
            myCommandBooks.Parameters.Add (myParameter1);

            OleDbParameter myParameter2 = new OleDbParameter();
            myParameter2.ParameterName = "@pub2";
            myParameter2.OleDbType = OleDbType.Integer;
            myParameter2.Value = DropDownList1.SelectedValue;
            myCommandBooks.Parameters.Add (myParameter2);
    
            myConnection.Open();
    
            DataGrid1.DataSource = myCommandBooks.ExecuteReader();
            DataGrid1.DataBind();
        }
        catch (Exception ex){
            throw(ex);
        }
        finally{
            myConnection.Close();
        }
    }

</script>
<html>
<head>
</head>
<body>
    <form runat="server">
        
            Select a Publisher: 
            <asp:DropDownList id="DropDownList1" runat="server"></asp:DropDownList>
            &nbsp; 
            <asp:Button id="Button1" onclick="ApplyFilter_Click" runat="server" Text="Show Titles"></asp:Button>
        
        <asp:datagrid id="DataGrid1" runat="server" EnableViewState="False">
            <HeaderStyle font-bold="True" forecolor="white" backcolor="#4A3C8C"></HeaderStyle>
            <ItemStyle backcolor="#DEDFDE"></ItemStyle>
        </asp:datagrid>
    </form>
</body>
</html>
18.11.OleCommand
	18.11.1.	OleCommand and OleParameter