They tried OO-like DB's in the 1960's, but they had many shortcomings. The biggest problem is that they generally lack a larger-scale structure on which to understand the forest-view and do high-level manipulations on. Relational has the "table" structure on which "relational math" can be done. (True, SQL often sucks, but that is the fault of the language, not the relational paradigm.) In relational you ask for what you want, not how to navigate to it. Thus, non-relational DB's are often called "navigational databases".

There has yet to be a "Dr. Codd of objects". Thus, OO is left with tangled seaweed as its highest-level formal structure. For more rants and info on this, see:

[link|http://c2.com/cgi/wiki?ModernDinosaur|http://c2.com/cgi/wiki?ModernDinosaur]

[link|http://www.geocities.com/tablizer/core1.htm|http://www.geocities...ablizer/core1.htm]