The database management systems can be classified based on several criteria. A. Based on data model: the relational data model; hierarchical data model; network data model; or object- oriented data models. B. Based on the number of users: single user database system which supports one user at a time or multiuser systems which support multiple users concurrently. C. Based on the ways database is distributed: Centralized Systems (the system is stored at a single site.); Distributed database system (Actual database and DBMS software are distributed in various sites connected by a computer network.) - Homogeneous distributed Database Systems or Heterogeneous distributed Database Systems.

Choose three different types of the database management systems. Do your research on these DBMS, explain and discuss about these different systems. (the main features, applications, comparisons of advantages or disadvantages.) Please cite the references (books, website, etc...)