This article is dedicated primarily to logical representation of objects in database by means of two object-relational (OR) languages: SQL3 (or SQL:1999) (http://www.objs.com/x3h7/sql3.htm) and Zigzag (http://savtechno.com). Really, the SQL3 is not final and is not supported by all the known object-relational DBMSs completely. The matter in hands of this article is object-oriented SQL of Oracle and Informix. Zigzag differs from SQL not only in syntax but also in methods of data processing. Whereas the SQL is a calculus language, the Zigzag is an algebra object-relational language.
The article continues at http://savtechno.com/SightOfORDBMS.html