C#

namespace Test {
	using System;
	using System.Threading;

	using Gtk;
	using Glade;
	using GtkSharp;

	public class Test
	{
		[Glade.Widget] private TextView textview1;
		[Glade.Widget] private Button button1;
		[Glade.Widget] private Window window1;

		private TextBuffer tb;

		private ThreadNotify tn;
		private Thread t;
		private int cnt = 0;

		// Constructor
		public Test()
		{
			Gtk.Application.Init();

			Glade.XML gxml = new Glade.XML (null, "test.glade", "window1", null);
			gxml.Autoconnect (this);

			tb = new TextBuffer(null);
			textview1.Buffer = tb;
			tn = new ThreadNotify( new ReadyEvent(Ready) );
			t = new Thread(new ThreadStart(Fill) );
			t.IsBackground = true;

			Application.Run();
		}

		public void Fill()
		{
			int i = 0;
			for ( ; ; )
			{
				cnt = i;
				i = (i < 100) ? (i + 1) : 0;
				tn.WakeupMain();
			}
		}


		public void Ready()
		{
			tb.Insert(tb.EndIter, cnt.ToString() + "\n");
	        }

		// DeleteWindow
		public void OnWindow1DeleteEvent (object o, DeleteEventArgs args) 
		{
			t.Abort();
			Application.Quit ();
		}

		public void OnButton1Clicked(object o, EventArgs args)
		{
			t.Start();
			button1.Sensitive = false;
		}

		public static void Main()
		{
			Test t = new Test();
		}
	}
}

public void button1_Click(object sender, System.EventArgs e) <br />
{ <br />
  OdbcDataReader myReader; <br />
  string myConnString = "DSN=MS Access  Database;DefaultDir=C:\\DOCUMENTS AND SETTINGS\\OWNER\\MY DOCUMENTS;DriverId=25;DBQ=C:\\DOCUMENTS AND SETTINGS\\OWNER\\MY DOCUMENTS\\login.mdb;MaxBufferSize=2048;FIL=MS Access;PageTimeout=5;UID=admin"; <br />
//string password; <br />
string mySelectQuery = "SELECT Username, Password FROM tblLogin WHERE Username = " + txtUserName.Text; <br />
OdbcConnection myConnection = new OdbcConnection(myConnString); <br />
OdbcCommand myCommand = new OdbcCommand(mySelectQuery,myConnection); <br />
myConnection.Open(); <br />
[CODE]myReader = myCommand.ExecuteReader();[/CODE] <br />
while(myReader.IsDBNull(0)) <br />
{ <br />
   lblErrorUser.Visible=true; <br />
}