Expressions as Data in Relational Data Base Management Systems

Numerous applications, such as publish/subscribe, website personalization, applications involving continuous queries, etc., require that user.s interest be persistently maintained and matched with the expected data. Conditional Expressions can be used to maintain user interests. This thesis focuses on the support for expression data type in relational database system, allowing storing of conditional expressions as .data. in columns of database tables and evaluating those expressions using an EVALUATE operator. With this context, expressions can be interpreted as descriptions, queries, and filters, and this significantly broadens the use of a relational database system to support new types of applications. The thesis presents an overview of the expression data type, storing the expressions, evaluating the stored expressions and shows how these applications can be easily supported with improved functionality. A sample application is also explained in order to show the importance of expressions in application context, with a comparison of the application with and without expressions

Object-oriented querying of existing relational databases

In this paper, we present algorithms which allow an object-oriented querying of existing relational databases. Our goal is to provide an improved query interface for relational systems with better query facilities than SQL. This seems to be very important since, in real world applications, relational systems are most commonly used and their dominance will remain in the near future. To overcome the drawbacks of relational systems, especially the poor query facilities of SQL, we propose a schema transformation and a query translation algorithm. The schema transformation algorithm uses additional semantic information to enhance the relational schema and transform it into a corresponding object-oriented schema. If the additional semantic information can be deducted from an underlying entity-relationship design schema, the schema transformation may be done fully automatically. To query the created object-oriented schema, we use the Structured Object Query Language (SOQL) which provides declarative query facilities on objects. SOQL queries using the created object-oriented schema are much shorter, easier to write and understand and more intuitive than corresponding S Q L queries leading to an enhanced usability and an improved querying of the database. The query translation algorithm automatically translates SOQL queries into equivalent SQL queries for the original relational schema

Relational Constraint Driven Test Case Synthesis for Web Applications

This paper proposes a relational constraint driven technique that synthesizes test cases automatically for web applications. Using a static analysis, servlets can be modeled as relational transducers, which manipulate backend databases. We present a synthesis algorithm that generates a sequence of HTTP requests for simulating a user session. The algorithm relies on backward symbolic image computation for reaching a certain database state, given a code coverage objective. With a slight adaptation, the technique can be used for discovering workflow attacks on web applications.Comment: In Proceedings TAV-WEB 2010, arXiv:1009.330