E-commerce systems involve a complex interaction between web-based Internet related software, application software and databases. It is clear that the success of e-commerce systems is going to be dependent not only on the technology of these systems but also on the quality of the underlying databases and supporting processes. Whilst databases have achieved considerable success in the wider marketplace, the main research effort has been on tools and techniques for high volume but based on relatively simplistic record management. The modern advanced e-commerce systems require a paradigm shift to allow the meaningful representation and manipulation of complex business information on the web and Internet. This requires the development of new methodologies, environments and tools to allow one to easily understand the underlying structure to facilitate access, manipulation and modification of such information. An essential characteristic to gain understanding and interoperability is a clearly defined semantics for e-commerce systems and databases. The focus of this volume is therefore on those issues of e-commerce systems that involve the semantics of the information represented, stored and manipulated by these systems. This not only includes methodologies for application domain modeling, formal representations of e-commerce aspects of knowledge, the role of semantics, Internet based transmission and display of data, and so on but also issues in user interfacing and process modelling, architectures that better enable integrity, consistency, interoperation reuse of components, or reports on prototypes illustrating new aspects of such systems from a semantically relevant viewpoint. The text comprises the proceedings of the Ninth Working Conference on Database Semantics, which was sponsored by the International Federation for Information Processing (IFIP) and held in Hong Kong in April 2001. This volume should be of interest to researchers and practitioners working in the areas of database management, information retrieval and data mining, and user interfaces, as applied to e-commerce.