Besides differentiating databases
according to function, databases can also be
differentiated according to how they model the data.
What is a data model?
a data model is a "description" of both a container for data and a
methodology for storing and retrieving data from that container. Actually,
there isn't really a data model "thing". Data models are abstractions,
oftentimes mathematical algorithms and concepts. You cannot really
touch a data model. But nevertheless, they are very useful. The analysis
and design of data models has been the cornerstone of the evolution of
databases. As models have advanced so has database efficiency.
Before the 1980's, the two most commonly
used Database Models were the hierarchical and network
systems. Let's take a quick look at these two models and then move on
to the more current models.