> -----Original Message----- > Behalf Of Mark Wonsil ... > The term relational comes from relational mathematics, i.e. set > theory. This is why there are union and intersection (join) functions. ... > ImageSQL *is* an SQL interface for Image, so Adam's point stands that > having an SQL interface does not a relational database make. Excellent summary Mark. Although SQL does not make a relational database, its development is closely linked, and I think that's why they are confused so often. The best explanation I've read of what a relational database is and how it was derived from set theory was published in a series of articles from Intelligent Enterprise magazine. Which starts at the link below http://www.intelligententerprise.com/db_area/archives/1998/9810/feat4.jhtml At the link below it finally gets into how Edgar F Cobb wanted to translate set theory in a computer language called Data Sublanguage Alpha. It was never implemented but it provide the basis for SQL. http://www.intelligententerprise.com/db_area/archives/1999/991602/online2.jhtml Jerry Finn The Migration Factory IBM Corporation 11400 Burnet Rd. Austin, TX 78758 http://www-1.ibm.com/servers/eserver/migration/ * To join/leave the list, search archives, change list settings, * * etc., please visit http://raven.utc.edu/archives/hp3000-l.html *