This paper discusses a problem that most of programmers fascinated by the object-oriented paradigm had to face: how to save objects? Almost all programming languages that support this paradigm solve the problem mainly by using data files. This type of support is not entirely satisfying especially when large amount of data is involved. As object-oriented platforms evolved, it has come out the possibility of saving objects, most of the cases, into a relational database. This solution requires the conversion of the object model into a relational model in order to allow the saving of objects. It still remains the problem regarding the interface between the language and the database management system and moreover the lack of a language for data manipulation. The answers to these problems consist of: (1) defining intermediate classes between the programming language and the database used and (2) using software packages that act as an interface between programming language and a database management system. In the second part of the paper we present, from both theoretical and practical point of view, the advantages of the two previously mentioned methods in what concerning the elegant alternatives for the implementation of the persistence concept, from the object-oriented paradigm.