> Note that “uniform service layer” doesn’t necessarily mean “networked service layer”, this can be in-process if you can prevent people from bypassing your querying functions and going directly to the DB.

You can take it one step further and implement the “uniform service layer” in the database itself - using stored procedures and views.

This has downsides, like strong coupling with the specific DBMS, and difficulty of development in a comparatively primitive SQL dialect, but protects the database from “naughty” clients and can have tremendous performance advantages in some cases.