The simple data editing web application I'll walkthrough building in this tutorial is a basic data entry/manipulation front-end for products within a database:

Figure 1

The application will support the following end-user features:

Allow users to filter the products by category

Allow users to sort the product listing by clicking on a column header (Name, Price, Units In Stock, etc)

Allow users to skip/page over multiple product listings (10 products per page)

Allow users to edit and update any of the product details in-line on the page

Allow users to delete products from the list

The web application will be implemented with a clean object-oriented data model built using the LINQ to SQL ORM.

All of the business rules and business validation logic will be implemented in our data model tier - and not within the UI tier or in any of the UI pages.  This will ensure that: 1) a consistent set of business rules are used everywhere within the application, 2) we write less code and don't repeat ourselves, and 3) we can easily modify/adapt our business rules at a later date and not have to update them in dozens of different places across our application.

We will also take advantage of the built-in paging/sorting support within LINQ to SQL to ensure that features like the product listing paging/sorting are performed not in the middle-tier, but rather in the database (meaning only 10 products are retrieved from the database at any given time - we are not retrieving thousands of rows and doing the sorting/paging within the web-server).