Re: When use triggers?

I've always found it most useful to consider the difference between "what
the system is" vs. "what the system does". The core data entities and their
stable relationships comprise most of what the system is. These are the
things that should be enforced at the lowest level possible (in a db
schema) and can be supported by other tools preferably as close to the
database as possible - such as triggers and stored procedures. The purpose
of these items should be strictly regulated to keeping the integrity of
these entities intact. They should not presume a particular usage model nor
should they implement application-specific business logic (which is
something that changes more frequently).

The various applications and businesses logic comprise "what the system
does". Those entities now play various (often dynamic) roles in the context
of your use cases. This is what should be implemented in your various
programming languages and should be independent of any specifics of your
database (or any particular UI as well if possible). This makes testing the
application much easier and your application is also easier to write if it
can assume that integrity constraints are already enforced at a lower level
by the DB itself. This business functionality generally should not be
implemented within the DB as it tightly couples the DB and the app which
gets really painful as the app evolves.

Hope that general set of policies helps guide your thinking and makes your
efforts more effective.

- - Ben Scherrey

On Thu, May 17, 2018, 5:20 AM hmidi slim <hmidi(dot)slim2(at)gmail(dot)com> wrote:

> HI,
>
> I'm working on a microservice application and I avoid using triggers
> because they will not be easy to maintain and need an experimented person
> in database administration to manage them. So I prefer to manage the work
> in the application using ORM and javascript.
> However I want to get some opinions and advices about using triggers: when
> should I use them? How to manage them when there are some problems?
>