Business Logic: Database or Application Layer

Question

The age old question. Where should you put your business logic, in the database as stored procedures ( or packages ), or in the application/middle tier? And more importantly

Answer 1

The business logic should be placed in the application/middle tier as a first choice. That way it can be expressed in the form of a domain model, be placed in source control, be split or combined with related code (refactored), etc. It also gives you some database vendor independence.

Object Oriented languages are also much more expressive than stored procedures, allowing you to better and more easily describe in code what should be happening.

The only good reasons to place code in stored procedures are: if doing so produces a significant and necessary performance benefit or if the same business code needs to be executed by multiple platforms (Java, C#, PHP). Even when using multiple platforms, there are alternatives such as web-services that might be better suited to sharing functionality.