This project concentrates on the TPC-H benchmark on Oracle 9i Enterprise Edition (EE) and DB2 Universal Database Version 7.2 Enterprise Edition (EE) on Windows2000 operating system. The TPC-H benchmark is a decision-support benchmark, consisting of a set of queries and refresh functions in order to simulate a real environment. There are several size factors supported by TPC to represent the database size. In this project, we use 1GB and 10GB database size. Furthermore, the test results are used to compare the performance of Oracle and DB2 on the Windows2000 operating system. Performance tuning is still a major issue in the database applications. There are two levels of tuning: system level and application level. We just focus on the application level tuning and study different factors and their effects on the DBMS' performance.