The first, unpublished, most underrated and brilliant paper by Codd, "Derivability, Redundancy, and Consistency of Relations Stored in Large Data Banks" - http:

The first, unpublished, most underrated and brilliant paper by Codd, "Derivability, Redundancy, and Consistency of Relations Stored in Large Data Banks" - http://www.liberidu.com/blog/images/rj599.pdf http://www.liberidu.com/blog/images/rj599.pdf > The true importance of relational theory is highlighted by the title of the original (and considerably shorter) version of Codd’s first paper. That version predated the published version by a year, and the title was “Derivability, Redundancy, and Consistency of Relations Stored in Large Data Banks.” The title of this unpublished version emphasizes that the real importance of relational theory is that it provides a rigorous method of asserting arbitrarily complex consistency constraints that must be satisfied by the data within the database. Strange as it may sound, Oracle Database did not enforce referential integrity constraints until Version 7 was released in the 1990s (by which time Oracle Corporation was already the world’s largest database company) https://iggyfernandez.wordpress.com/2013/04/24/whats-so-sacred-about-relational-anyway/3/ https://iggyfernandez.wordpress.com/2013/04/24/whats-so-sacr...