published 20 Oct 1995 : 01 Jan 1996 updated
Why are relational databases called "relational"? Is it, as most people confidently surmise, because we "relate" tables to each other through values in columns? Well, contrary to popular opinion and common sense, the real answer is a little bit more arcane.
Edgar Codd first wrote about the concept of relational databases in his paper "A Relational Model of Data for Large Shared Data Banks" in 1970. He was using the term "relation" in the strict mathematical sense of a table with a few special properties. Thus Codd was describing a system where all of the database - data, structure, rules - is housed in simple tables of rows and columns. While this may seem obvious to us today, it was by no means obvious in 1970.
Codd went on to define relational databases more completely in {Codd74} where he laid out twelve principle of relational databases. His most recent work expands the list to 333 requirements in {Codd90}.
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Copyright © 1995 Applied Information Science International; 20 Oct 1995