Comment by loldot_

Exactly! If you're writing a C compiler, it would probably be a bad idea to have that logic in a database, though it could be fun to try. On the other hand if your application is summarizing a lot data by different dimensions, it would probably be a bad idea to transfer all that data over the network only to summarize it in an application layer. Most applications have a little bit of both though and so will need both an application layer and database layer.