This system replaces hierarchical database management system and network database management system. Because of relational database management systems easier to use than hierarchical database management system and network database management system. But object-oriented database management system and XML database produce challenges to relational database management systems.
If the relation between two fields defined as many to many, then the system is called as network management system. The database system in which system described in the form of the object then its called as the object-oriented database management system.
Object-oriented system store more complex data than Relational database management system, without using relation.