Master-detail relationships exist in all databases. For example, the Northwind database has a three-level master-detail relationship. Customers is referenced by Orders, and Orders is referenced by Order Details.
![Customers, Orders, and Order Details table relationships in Northwind database Customers, Orders, and Order Details table relationships in Northwind database](/blog/2012/05/feature-multi-level-master-detail-pages/image02.png)
Code On Time web application generator automatically creates two-level master-detail pages. You can extend any master-detail page to have more relationship levels. An extended three-level master-detail page is shown below.
![Three-Level Master-Detail page in Northwind web application. Three-Level Master-Detail page in Northwind web application.](/blog/2012/05/feature-multi-level-master-detail-pages/image04.png)
![Three-Level Master-Detail page in Northwind web application. Three-Level Master-Detail page in Northwind web application.](/blog/2012/05/feature-multi-level-master-detail-pages/image06.png)