The data modeling phase is one of the main phases in automated system development methods. Usually data modeling is separated as independent process which success and robustness depends largely on the intuition and experience of the data analyst. This can become problematic when IS database is being designed for large scale IS. To solve this type of problems it’s proposed to accomplish data modeling phase not as a separate, poorly with the generic modeling process connected part but as one of the fundamental system development phases. Functional Requirements Specification Method is proposed for this matter. This methods main idea is to build database model according to user requirements for the functionality of the system being developed. The purpose of this work is to present a process intended for building a entity relationship diagram from the analysed functional requirements specification metamodel and generation of the SQL DDL script (relational schema) from that model. The presented model will be implemented as one of the CASE tool modules specified for the database modeling and SQL DDL script generation. Implemented tool will be verified and it’s correctness will be experimentally approved.