Data warehouse is one of the most rapidly growing areas in management information system. With this approach, data for Executive Information System (EIS) and Decision Support System (DSS) applications are separated from operational data and stored in a separate database. This process is called data warehousing. The major advantages of this approach are: improved in performance, better data quality, and the ability to consolidate and summarize data from heterogeneous systems. A data warehouse is part of a larger infrastructure that includes legacy data sources, external data sources, a repository, data acquisition software, and user interface and related analytical tools.