Ask HN: Finance industry devs, where do you put the business logic, DB or Code

If your answer is "majority in db" then how do you combat arguments like:

* You can't test/debug BL in DB (or it's very hard)

* You can't do continuous integration

* The code a mess and hard to maintain/make sense of

If your answer is "majority in app":

* Do you have an API on top of DB that enforces the rules?

* Is the security/data validation also done in the API/app layer?