(C#) ASP.NET DataGrid Control - ItemCommand

<%@ Page Language="C#" Debug="true" %>
<%@ import Namespace="System.Data" %>
<%@ import Namespace="System.Data.OleDb" %>
<script runat="server">
	OleDbConnection objConn;
	OleDbCommand objCmd;
	String strSQL;

    void Page_Load(object sender,EventArgs e)
	{
		String strConnString;
		strConnString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + 
		Server.MapPath("database/mydatabase.mdb") + ";";
		objConn = new OleDbConnection(strConnString);
		objConn.Open();
		
		if(!Page.IsPostBack)
		{
			BindData();
		}
    }

	void BindData()
	{
		String strSQL;
		strSQL = "SELECT * FROM customer";

		OleDbDataReader dtReader;
		objCmd = new OleDbCommand(strSQL, objConn);
		dtReader = objCmd.ExecuteReader();
		
		//*** BindData to DataGrid ***//
		myDataGrid.DataSource = dtReader;
		myDataGrid.DataBind();

		dtReader.Close();
		dtReader = null;

	}

	void Page_UnLoad()
	{
		objConn.Close();
		objConn = null;
	}

	void modEditCommand(Object sender, DataGridCommandEventArgs e)
	{
		myDataGrid.EditItemIndex = e.Item.ItemIndex;
		myDataGrid.ShowFooter = false;
		BindData();
	}

	void modCancelCommand(Object sender, DataGridCommandEventArgs e)
	{
		myDataGrid.EditItemIndex = -1;
		myDataGrid.ShowFooter = true;
		BindData();
	}

    void myDataGrid_ItemCommand(Object sender , DataGridCommandEventArgs e)
	{
        if (e.CommandName == "Add")
        {
            //*** CustomerID ***//
            TextBox txtCustomerID = (TextBox)e.Item.FindControl("txtAddCustomerID");
            //*** Email ***//
            TextBox txtName = (TextBox)e.Item.FindControl("txtAddName");
            //*** Name ***//
            TextBox txtEmail = (TextBox)e.Item.FindControl("txtAddEmail");
            //*** CountryCode ***//
            TextBox txtCountryCode = (TextBox)e.Item.FindControl("txtAddCountryCode");
            //*** Budget ***//
            TextBox txtBudget = (TextBox)e.Item.FindControl("txtAddBudget");
            //*** Used ***//
            TextBox txtUsed = (TextBox)e.Item.FindControl("txtAddUsed");

            strSQL = "INSERT INTO customer (CustomerID,Name,Email,CountryCode,Budget,Used) " +
                " VALUES ('" + txtCustomerID.Text + "','" + txtName.Text + "','" + txtEmail.Text + "' " +
                " ,'" + txtCountryCode.Text + "','" + txtBudget.Text + "','" + txtUsed.Text + "') ";
            objCmd = new OleDbCommand(strSQL, objConn);
            objCmd.ExecuteNonQuery();

            BindData();
        }		
    }

	void modDeleteCommand(Object sender, DataGridCommandEventArgs e)
	{
		strSQL = "DELETE FROM customer WHERE CustomerID = '" + myDataGrid.DataKeys[e.Item.ItemIndex] + "'";
		objCmd = new OleDbCommand(strSQL, objConn);
		objCmd.ExecuteNonQuery();

		myDataGrid.EditItemIndex = -1;
		BindData();
	}

	void modUpdateCommand(Object sender,DataGridCommandEventArgs e)
	{
        //*** CustomerID ***//
        TextBox txtCustomerID = (TextBox)e.Item.FindControl("txtEditCustomerID");
        //*** Email ***//
        TextBox txtName = (TextBox)e.Item.FindControl("txtEditName");
        //*** Name ***//
        TextBox txtEmail = (TextBox)e.Item.FindControl("txtEditEmail");
        //*** CountryCode ***//
        TextBox txtCountryCode = (TextBox)e.Item.FindControl("txtEditCountryCode");
        //*** Budget ***//
        TextBox txtBudget = (TextBox)e.Item.FindControl("txtEditBudget");
        //*** Used ***//
        TextBox txtUsed = (TextBox)e.Item.FindControl("txtEditUsed");

        strSQL = "UPDATE customer SET CustomerID = '" + txtCustomerID.Text + "' " +
            " ,Name = '" + txtName.Text + "' " +
            " ,Email = '" + txtEmail.Text + "' " +
            " ,CountryCode = '" + txtCountryCode.Text + "' " +
            " ,Budget = '" + txtBudget.Text + "' " +
            " ,Used = '" + txtUsed.Text + "' " +
            " WHERE CustomerID = '" + myDataGrid.DataKeys[e.Item.ItemIndex] + "'";
        objCmd = new OleDbCommand(strSQL, objConn);
        objCmd.ExecuteNonQuery();

        myDataGrid.EditItemIndex = -1;
        myDataGrid.ShowFooter = true;
        BindData();		
	}

</script>
<html>
<head>
    <title>ThaiCreate.Com ASP.NET - DataGrid</title>
</head>
<body>
<form id="form1" runat="server">
<asp:DataGrid id="myDataGrid" runat="server" AutoGenerateColumns="False" 
	ShowFooter="True" 
	DataKeyField="CustomerID"
	OnEditCommand="modEditCommand"
	OnCancelCommand="modCancelCommand"
	OnDeleteCommand="modDeleteCommand"
	OnUpdateCommand="modUpdateCommand"
	onItemCommand="myDataGrid_ItemCommand">

	<Columns>

	<asp:TemplateColumn HeaderText="CustomerID">
		<ItemTemplate>
			<asp:Label id="lblCustomerID" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.CustomerID") %>'></asp:Label>
		</ItemTemplate>
		<EditItemTemplate>
			<asp:TextBox id="txtEditCustomerID" size="5" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.CustomerID") %>'></asp:TextBox>
		</EditItemTemplate>
		<FooterTemplate>
			<asp:TextBox id="txtAddCustomerID" size="5" runat="server"></asp:TextBox>
		</FooterTemplate>
	</asp:TemplateColumn>

	<asp:TemplateColumn HeaderText="Name">
		<ItemTemplate>
			<asp:Label id="lblName" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.Name") %>'></asp:Label>
		</ItemTemplate>
		<EditItemTemplate>
			<asp:TextBox id="txtEditName" size="10" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.Name") %>'></asp:TextBox>
		</EditItemTemplate>
		<FooterTemplate>
			<asp:TextBox id="txtAddName" size="10" runat="server"></asp:TextBox>
		</FooterTemplate>
	</asp:TemplateColumn>

	<asp:TemplateColumn HeaderText="Email">
		<ItemTemplate>
			<asp:Label id="lblEmail" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.Email") %>'></asp:Label>
		</ItemTemplate>
		<EditItemTemplate>
			<asp:TextBox id="txtEditEmail" size="20" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.Email") %>'></asp:TextBox>
		</EditItemTemplate>
		<FooterTemplate>
			<asp:TextBox id="txtAddEmail" size="20" runat="server"></asp:TextBox>
		</FooterTemplate>
	</asp:TemplateColumn>

	<asp:TemplateColumn HeaderText="CountryCode">
		<ItemTemplate>
			<asp:Label id="lblCountryCode" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.CountryCode") %>'></asp:Label>
		</ItemTemplate>
		<EditItemTemplate>
			<asp:TextBox id="txtEditCountryCode" size="2" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.CountryCode") %>'></asp:TextBox>
		</EditItemTemplate>
		<FooterTemplate>
			<asp:TextBox id="txtAddCountryCode" size="2" runat="server"></asp:TextBox>
		</FooterTemplate>
	</asp:TemplateColumn>

	<asp:TemplateColumn HeaderText="Budget">
		<ItemTemplate>
			<asp:Label id="lblBudget" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.Budget") %>'></asp:Label>
		</ItemTemplate>
		<EditItemTemplate>
			<asp:TextBox id="txtEditBudget" size="6" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.Budget") %>'></asp:TextBox>
		</EditItemTemplate>
		<FooterTemplate>
			<asp:TextBox id="txtAddBudget" size="6" runat="server"></asp:TextBox>
		</FooterTemplate>
	</asp:TemplateColumn>

	<asp:TemplateColumn HeaderText="Used">
		<ItemTemplate>
			<asp:Label id="lblUsed" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.Used") %>'></asp:Label>
		</ItemTemplate>
		<EditItemTemplate>
			<asp:TextBox id="txtEditUsed" size="6" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.Used") %>'></asp:TextBox>
		</EditItemTemplate>
		<FooterTemplate>
			<asp:TextBox id="txtAddUsed" size="6" runat="server"></asp:TextBox>
			<asp:Button id="btnAdd" runat="server" Text="Add" CommandName="Add"></asp:Button>
		</FooterTemplate>
	</asp:TemplateColumn>

	<asp:EditCommandColumn ButtonType="LinkButton" UpdateText="Update" CancelText="Cancel" EditText="Edit" HeaderText="Modify" ></asp:EditCommandColumn>
	<asp:ButtonColumn Text="Delete" CommandName="Delete" HeaderText="Delete"></asp:ButtonColumn>
	
	</Columns>
</asp:DataGrid>
</form>
</body>
</html>