fication number was inevitably user provided. The database is not only used for storing data but also pieces of code (methods) that run onthe data. Consequently, a whole application can be stored and executed with the help of theOODBMS that also supports its maintenance. The inheritance concept makes code easily reusable. The expensive join operations of the relational systems have been substituted by thecomposite object notion, which combined with the clustering mechanism can improve theperformance of the composite object retrieval.There are many applications that have been using the relational systems very successfullynow for many years and they do not need to change. However, there are a couple of otherapplications especially in the engineering fields that don't do much with relational systems,mainly from the modeling aspect. For these kinds of applications, the object-orientedapproach seems quite appropriate in spite of the problems that still have to be solved....
