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.

Semantics in Databases.- Characterizing and Computing Semantically Correct Answers from Databases with Annotated Logic and Answer Sets.- Towards Unifying Semantic Constraints and Security Constraints.- Historical and Computational Aspects of Paraconsistency in View of the Logic Foundation of Databases.- Soft Constraints and Heuristic Constraint Correction in Entity-Relationship Modelling.- Characterization of Type Hierarchies with Open Specification.- Null Values in Relational Databases and Sure Information Answers.- Consistency Enforcement in Databases.- Automata- and Logic-Based Pattern Languages for Tree-Structured Data.- Cardinality Constraints in Disjunctive Deductive Databases.- Semantic Classifications of Queries to Relational Databases.