A data analysis system for the general commodity sales information is researched on and further designed. The key problems of designing this system are that, it should enable the system to adjust to user-data with different structures, enable users to define or change data structures as well as retrieval methods. Through the research on the general structure and retrieval method of the commodity sales data, the system realizes users' customization of the database, thus is applicable to sales data with different structures. This paper focuses on the structure of the database, the creation method and process of the database by the user, the structure of the data dictionary and data exchange between database and software, with case examples in the final illustration.