In this 3rd edition of The Third Manifesto, the authors have, in their own words, stripped the 'polemics'and added exercises to facilitate tuition.

This is a further refinement and expansion of their blueprint for a truly relational Database Management System (DBMS). It is fair to say that they are not influenced in the slightest by vendor concerns, and that is a refreshing but sadly diminishing trait in these computing times. Consequently, they will always call a spade a spade, and will not be shy is so stating. Therefore NULLs and duplicate tuples, for example, will always be abominations to be repulsed totally in any database that aspires to the 'relational' label.

Throughout all of their work concerning the Relational Model (RM), the first and foremost inspiration for which is of course E.F. Codd, there prevail several fundamental and immutable themes that are given full treatment in this volume: strict adherence to the mathematics of the RM (no NULLs, duplicates, etc.), clear separation of the logical and the physical (so often muddled together), the orthogonality of data types within the RM (data types do not impinge on or compromise the RM, and vice versa), proper and comprehensive declarative integrity constraints within the DBMS (no current SQL DBMS provides anything like full integrity constraint support), the many deficiencies of SQL (bearing in mind that Darwen and Date produced what is perhaps the definitive SQL reference in 'The SQL Standard') and therefore necessitating a better language (which they have devised, and called it 'D'). No physical aspects of implementing the authors' recommendations are considered in this book, and nor should they be.

Anyone who has clocked up any degree of significant experience on SQL DBMSs will surely have had 'fun' with duplicate, triplicate, quadruplicate, etc., rows, or having totally incorrect results returned because NULLs have not been handled correctly; not to mention severe data integrity issues, or the quirks of SQL.

I have no doubt that had DBMSs from their inception adhered to principles similar to those as laid forth in this volume, DBMS professionals would have had much less 'fun', and end users would have had much more confidence in the data returned to them. It may be very late in the day where the major DBMS vendors are concerned, but hope springs eternal (almost).