Introduction
The intention of this site is to present a simple, concise, and precise exposition of the relational model emphasising its foundations in first order predicate logic.
In the context of finite model theory, a relational database schema is a theory — consisting of semantic predicates and axioms (expressed mostly as dependencies including functional dependencies) — which axiomatises all valid database instances, which are then models of that theory. More tentatively, I suspect that what is commonly called “the relational model” is closer to being an institution (in the Goguen & Burstall sense).
This is not as scary as it sounds. In fact, it is surprisingly easy to understand and reveals the beauty and simplicity of the relational model, as opposed to the often mathematically unsound and uniformly turgid treatment of the standard texts. This view of the relational model leads to a deep understanding at the expense of a little “up-front” effort in understanding formal logic.
The relational model is elegant and simple. No justice is done to it by 1,000-page textbooks, which uniformly confuse theory and implementation (often despite claims to the contrary), mix semantics with syntax, introduce dubious and unecessary concepts, and digress into XML and object-orientation.
When Will it be Ready?
Whenever I get time :-(
Cover Picture
The long-standing cover picture on this site is a parody of the religious dichotomy in the database field, not an endorsement of either side. If anything, this site is intended to represent a “Third Way”.
