Difference between MVC controller and business logic (3 tier)

I have been trying to find the different between MVC and 3-tier architecture in ASP.NET. I referred to some previous some previous questions and some pages, but could find a clear answer.
Here is a a msdn page about MVC implementation: http://msdn.microsoft.com/en-us/library/ff647462.aspx

Consider, I ahve this code:
Single page aspx UI and code as well

<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<html>
   <head>
      <title>start</title>
      <script language="c#" runat="server">
         void Page_Load(object sender, System.EventArgs e)
         {
            String selectCmd = "select * from Recording";

            SqlConnection myConnection = 
               new SqlConnection(
                  "server=(local);database=recordings;Trusted_Connection=yes");
            SqlDataAdapter myCommand = new SqlDataAdapter(selectCmd, 
               myConnection);

            DataSet ds = new DataSet();
            myCommand.Fill(ds, "Recording");

            recordingSelect.DataSource = ds;
            recordingSelect.DataTextField = "title";
            recordingSelect.DataValueField = "id";
            recordingSelect.DataBind();
         }
       </script>
   </head>
   <body>
         <asp:dropdownlist id="recordingSelect" runat="server" />
         <asp:button runat="server" text="Submit" OnClick="SubmitBtn_Click" />
      </form>
   </body>
</html>

Now, consider I have different files for
---- View and Code-behind spearated ----
.aspx

<%@ Page language="c#" Codebehind="Solution.aspx.cs" 
   AutoEventWireup="false" Inherits="Solution" %>
<html>
         <asp:dropdownlist id="recordingSelect" runat="server" />
      </form>
   </body>
</html>

.aspx.cs

using System;
using System.Data;
using System.Data.SqlClient;
public class Solution : System.Web.UI.Page
{
   private void Page_Load(object sender, System.EventArgs e)
   {
      if(!IsPostBack)
      {
         String selectCmd = "select * from Recording";
         SqlConnection myConnection = 
            new SqlConnection(
               "server=(local);database=recordings;Trusted_Connection=yes");
         SqlDataAdapter myCommand = new SqlDataAdapter(selectCmd, myConnection);
         DataSet ds = new DataSet();
         myCommand.Fill(ds, "Recording");
         recordingSelect.DataSource = ds;
         recordingSelect.DataTextField = "title";
         recordingSelect.DataValueField = "id";
         recordingSelect.DataBind();
      }
   }

Seeing the above msdn page link for the Controller class, I am not able to discern the difference between the business logic (that would have been similar for a middle tier in a 3 tier architecture) and the controller.
Is 3-tier and MVC completely different thing? Are the ASP.NET application in Visual Studio already separated file as in MVC form? If these are not different, which one is the preferred style?
What's the MVC framework about then if the .aspx and .aspx.cs are already spearated?

Solution

I actually strugled with this a while myslef, there are different philosophies on how to implement it correctly, so this is how I understand it in my own words how I understand the relation between the different things involved (Models/Views/Controllers/Business Logic):

Views
Have all the Html / jQuery code, they use the data in form of Model instances that come from the controller
Models
The classes that hold the information your View needs to render (List of products etc)
Controllers
- They take incoming requests
- Make the necessary preparations (parameter extraction etc.) to call your actual business logic code.
- Then the call into the business logic code and retrieve the result
- Afterwards they take the result and transforms it into a Model that the UI understands
Business logic
This is your actual business logic code, calling the db etc. I my eyes this is totally separate from the entire MVC thing, in fact it should not even know it is executed from a MVC web application. Usually we put this in a different assembly (class library) to make sure there is no dependency to MVC code at all.
This makes it very simple to unit test just the business logic, since there are no dependencies to MVC.

I have seen other approaches where the business logic is actually put into the controllers, but in my eyes that defeats the purpose. We are not building MVC applications to have a nice structure, but also to be able to perform unit test better.

Getting back to your question, how does it all relate to ASP.NET 3-tier architecture.
One could say that basically the entire MVC web application is nothing more the Presentation layer (+ wireing up the Presentation layer with the Busines layer).

The other layers stay separate and independent from the presentation layer, as they should have before.