Correct operation of many critical systems is dependent on the data consistency and integrity properties of underlying databases. Therefore, a verifiable and rigorous database design process is highly desirable. This research aims to investigate and deliver a comprehensive and practical approach for modelling databases in formal methods through layered refinements. The methodology is being guided by a number of case studies, using abstraction and refinement in UML-B and verification with the Rodin tool. UML-B is a graphical representation of the Event-B formalism and the Rodin tool supports verification for Event-B and UML-B. Our method guides developers to model relational databases in UML-B through layered refinement and to specify the necessary constraints and operations on the database.