This thesis describes the process of transforming information system through the theoretical basis related to the design of information systems, process modeling, data modeling, and practical examples of different data models. Examples taken in this paper, passing phases of the life cycle of building new information systems, and differ in data models and databases that support it. Example "Log and deflection failures interference for fixed telephony, as part of the existing information systems in the telecommunications company, is based on network data model and implemented on the Digital Alpha computers under the VMS operating system. The application is written in PL / I programming language, and data are stored in network database CINCO TOTAL. Example "SAP IS-U solution, as part of a new information system in the electricity company, is based on object-relational data model in Oracle technology and SAP applicative interface. The process of planning the study, includes analysis of current information systems in order to accurately get all of the requirements under the new IT system. Throughout the design phase, the detailed requirements analysis are done and the conceptual model defined. In this phase, a process model and data model for a new information system, are defined in order to define a logical database model. Construction phase, for example for SAP IS-U system, is in accordance with the phase of realization of the standard methodology of implementation of SAP solutions (ASAP). In this phase, SAP IS-U system will be configured and adapted to the requirements defined in the previous phase, thoroughly tested in several cycles functionally and technically. At the end of this phase, there will be performed the extensive integration tests, which must confirm and verify the compatibility of SAP IS-U system with the definition of business processes are described through the design phase. Also, there will be tested and verified all required additional development, the concept of reporting, the concept of roles and authorizations.