Federated Database Management Systems (FDBS) are very complex. Component databases can be heterogeneous, autonomous and distributed, accounting for these different characteristics in building a FDBS is a difficult engineering problem. The Common Data Model (CDM) is what is used to represent the data in the FDBS. It must be semantically rich to correctly represent the data from diverse component databases which differ in structure, datamodel, semantics and content. In this research project we look at the complexity of the FDBS and examine which datamodel is most suited for th e CDM. A good metad a ta interface and query language is essential for th e CDM because merging component databases into the FDBS and maintaining and building the FDBS rely on a complete metadata interface and query language. In this research project we analyse the metadata interface and query language of the Object-Relational datamodel with a view to use it as the CDM. Distributed Component databases in a FDBS need to be merged in to the FDBS, current tools can not completely automate this process, we examine these problems and present a mobile solution.