This book constitutes the refereed proceedings of the 7th International Conference on Database Theory, ICDT'99, held in Jerusalem, Israel, in January 1999. The 26 revised full papers presented were carefully reviewed and selected from a total of 89 submissions. Also included are one full invited paper, an abstract of an invited talk, and the summary of a tutorial. The papers are organized in topical sections on query languages, logic, performance, concurrency and distribution, constraint databases, index structures, semi-structured data, mediation, computational issues, and views.

The Fourth International Workshop on Database Programming Languages - Object Models and Languages (DBPL-4) took place in Manhattan, New York City, 30 August-1 September 1993. The areas of interest and the format of DBPL-4 focused on the integration of programming languages, object models, type systems and database systems. As in the previous DBPL workshops, the setting was informal, allowing the participants to actively discuss and argue about the ideas presented in the talks. The comments and remarks made by the participants during and after the presentations were taken into account in the preparation of the final versions of the papers. The result, we believe, is a set of excellent papers. The DBPL sequence is closely related to the sequence of International Workshops on Persistent Object Systems (POS), first started in 1985. While the DBPL workshops focus on language and model issues, the POS workshops have focused on implementation issues; thus the two sequences complement each other. Many researchers participate in both workshop series. The eight sessions of the technical program of DBPL-4 were as follows: 1. Bulk types and their query languages (two sessions). 2. Object models and languages. 3. Data types with order. 4. Mechanisms to support persistence, reflection, and extensibility. 5. Query optimization and integrity constraints. 6. Logic-based models. 7. Implementation and performance issues.

The Fourth International Workshop on Database Programming Languages - Object Models and Languages (DBPL-4) took place in Manhattan, New York City, 30 August-1 September 1993. The areas of interest and the format of DBPL-4 focused on the integration of programming languages, object models, type systems and database systems. As in the previous DBPL workshops, the setting was informal, allowing the participants to actively discuss and argue about the ideas presented in the talks. The comments and remarks made by the participants during and after the presentations were taken into account in the preparation of the final versions of the papers. The result, we believe, is a set of excellent papers. The DBPL sequence is closely related to the sequence of International Workshops on Persistent Object Systems (POS), first started in 1985. While the DBPL workshops focus on language and model issues, the POS workshops have focused on implementation issues; thus the two sequences complement each other. Many researchers participate in both workshop series. The eight sessions of the technical program of DBPL-4 were as follows: 1. Bulk types and their query languages (two sessions). 2. Object models and languages. 3. Data types with order. 4. Mechanisms to support persistence, reflection, and extensibility. 5. Query optimization and integrity constraints. 6. Logic-based models. 7. Implementation and performance issues.

Abstract: "Advanced database applications demand new data modeling constructs beyond those available in relational databases. These include both new data structures, e.g. arrays and quadtrees, and an integration with the object-oriented programming paradigm. Declarative object-oriented query languages transfer the burden of choosing an efficient execution plan to the database query optimizer. The lack of a generally accepted object-oriented data model and the trend towards extensible systems demand an extensible framework for object-oriented query optimization. We suggest such an algebraic optimization framework which is based on the computational metaphor of processing bulk data.

Abstract: "This paper presents a logical model for an active object oriented database. The main idea is to use standard concepts of OODB such as encapsulation and inheritance. In particular triggers are special methods encapsulated in the appropriate object. The execution model uses nested transactions. The model is shown to be flexible and to generalize previous proposals."