Database is a core component the Electronic Health Record (EHR) system, and creating a data model for that database is challenging due to the EHR system special nature. Because of complexity, spatial, sparseness, interrelation, temporal, heterogeneity, and fast evolution of EHR data, modeling its database is complex process. This paper tried to build dynamic, complete and stable data model for EHR database. There are a little work and standards in this aspect because of its difficulty. We will use object relational modeling approach and entity attribute value with classes and relationships to build the model. This design facilitates and enhances the operations of data mining and decision support which is integrating component of an EHR system.