Abstract: Database design is a key step between requirement analysis and system implementation in information system engineering.According to the result of requirement analysis,traditional approaches of database design utilize human constructive thinking to abstract objects and their relationships.Since traditional approaches have some defects in describing data structures and relationships,especially for relationships between data items,the results of these approaches may deviate from the real situation.In this paper,we presented a new database design tool－data flowing direction graph(DFDG) to represent objects,relationships and relationships between data items.Our cases show that results of DFDG enjoy more simple,clear,correct and unambitious than those of former methods and can improve the correctness and reliability of information system while shortening implementing time needed.

Key words: Database design,Data source-target digraph,Directed graph