Should a database abstraction layer/data access layer also be an ORM? -

Should a database abstraction layer/data access layer also be an ORM? -

i'm curious whether should combine part of software responsible retrieving info database part returns objects application logic layer. benefits have? considerations need aware of?

does create difference database have pretty dynamic/loose schema?

my plan @ moment separate application 4 distinct parts:

database - document-oriented, going utilize mongodb. abstraction/access/orm layer - not sure whether should 3, or combination don't yet know plenty things consider, 1 reason came inquire here. application logic layer/business engine - responsible (you guessed) application logic , such. interface layer - responsible providing quick easy way generate dynamic ui elements.

can experienced offer immediate thoughts on general overview? comments appreciated.

orm abstraction project-planning