stored procedure examples I am wondering if there are examples of open source apps that are written in stored procedures? I read a lot about them in textbooks and would like to see how they are used in practice beyond implementing simple functionalities. One example that I found is the DBT benchmark implementations (http://sourceforge.net/apps/mediawiki/osdldbt) using stored procedures. If there are other similar applications I'd love to learn about them.

@a_horse_with_no_name: thanks for your pointer. Apps like LedgerSMB that makes heavy uses of stored procedures are exactly those that I am looking for. If there are other similar ones please let me know.
I doubt there are many applications that are completely written in stored procedures. Doing a (sophisticated) user interface based on a procedural language in a DBMS is pretty hard to do (depending on the DBMS maybe even impossible). 

Oracle's APEX (APlication EXpress) is geared toward that, but the UI is still HTML - although it is generated generated through stored procedures if I'm not mistaken.

One application I know of that makes heavy use of stored procedures as part of the business logic is LedgerSMB: http://ledgersmb.org/