Database/Data Access Layer (DAL)

Related to my previous writing about MVC, there is other thing that I'd like to share. Previously, I wrote that MVC helped a lot in creating a big (enterprise?) application. While MVC defines layers that represent layer in same level, DAL (Data Access Layer) provides a depth in application abstraction. DAL logically inserted below business process layer to provide independent-to-database access. The DAL itself contains implementation to specific database access and also interfaces to business process layer.



The benefit of DAL is not far difference with MVC. By separating business process with data access, we may create several implementation of data access (to MySQL, MSSQL, Oracle, etc) without having problems changing the business process.