Object-relational mapping (ORM, O/RM, and O/R mapping tool!) in computer science is a programming technique for converting data between incompatible type systems using object-oriented programming languages. This creates, in effect, a "virtual object database" that can be used from within the programming language. There are both free and commercial packages available that perform object-relational mapping, although some programmers opt to construct their own ORM tools. In object-oriented programming, data-management tasks act on objects that are almost always non-scalar values. For example, consider...