This book constitutes the thoroughly refereed post-proceedings of the Second International Workshop on Semantics in Databases, held in Dagstuhl Castle, Germany, in January 2001.

The 10 revised full papers presented together with an introduction by the volume editors were carefully selected during two rounds of reviewing. Among the aspects of database semantics discussed are semantic constraints, paraconsistency, logic foundations of databases, ER modeling, type hierarchies, null values, consistency enforcement, logic-based pattern languages, and semantic classification of queries. Among the classes of databases dealt with are deductive databases, relational databases, distributed information systems, and tree-structured data.