This volume is the proceedings of the second International Conference on Database Theory (ICDT) held in Bruges, Belgium, August 31 - September 2, 1988. ICDT intends to provide a European forum for the international research community working on theoretical issues related to database and knowledge base systems. The proceedings of this conference contain all invited and accepted papers, which represent the latest results obtained in ongoing research in database theory worldwide. Most major themes of research in database theory are covered in ICDT '88: the relational model, logic and databases, object-oriented databases, deductive databases, conceptual models, analysis and design of data structures, query languages, concurrency control and updates and transactions.