ABSTRACT
Database was initially used to support the processing of applications of the large amounts of structured data[1]. Traditional database was mainly used to organize and manage the data. Nevertheless, with the development of technology, traditional database start to show some limitations: 1) cannot be able to express complex objects of the objective word and is lack of support of the complex data types; 2) impedance mismatch and semantic fault; 3) lack of the ability of managing knowledge and object; 4) cannot be able to express the relationship between object and natural watwork; 5) cannot meet the need of application because of the data type[2][3]. In order to overcome the limitation of the traditional database described above, fortunately, with the development of the ObjectOriented technology, the Object-Oriented database finally generates. There are two approaches to combine the Object-Oriented technology and the database technology: one approach is to build the pure ObjectOriented Database Management System (OODBMS) by using the Object-Oriented language and increasing the functionality of the database. This approach can
support the persistent objects and can realize the sharing of the data, but it is difficult for developing and achieving the data conversion[4]. Another approach is to build an intermediate layer on the currently-mature relational database system, and this layer realizes the conversion from the relational data model to the Object-Oriented data model. This approach is considered as the best scheme between object technology and the traditional relational database.
