Using Business Data Connectivity Services (BCS) you can view data from your Line of Business (LOB) Applications with same look and feel as a SharePoint list with no code. You can also create custom SQL tables in your SQL databases, and using BCS you can create CRUD applications in SharePoint where the data appears as SharePoint Lists complete with Create, Read, Update and Delete (CRUD) Forms. At first the possibilities seem endless but there are several caveats to over come before you can make a complete business process solution, over and above simple lists that Sharepoint provides.
This blog post comes with a streaming video that will show you a business problem and how to solve it with BCS. This results in a technical problem and how one way to overcome that one. The LOB data is Job Posting from HR system with associated incumbents, where data is read only and we have to track comments entered by users who peruse the job posting in SharePoint. You cannot just simply add a writable custom field to the read only job posting tables and lists. We do not have the time and money to write custom code to solve the problem. We have to use tools that SharePoint offers, and I have chosen to use SharePoint Designer, InfoPath Designer and a Custom List.
See the link to the video below, showing the complete steps, how to configure SQL tables, BCS, Secure Store, Custom List and custom InfoPath Form. See here