C. J. Date is an independent author, lecturer, researcher, and consultant, specializing in relational database technology (a field he helped pioneer). Before leaving IBM in 1983, he was involved in technical planning and design for the IBM products SQL/DS and DB2. His book An Introduction to Database Systems (8th edition 2003) is the standard text on the subject; it has sold well over 650,000 copies and is used by several hundred colleges and universities worldwide. He is also the author of many other books on database management, including in particular Foundation for Future Database Systems: The Third Manifesto (2nd edition 2000, with Hugh Darwen).
