ResumenSemantic Analysis of SQL Statements in DESSáenz Pérez, Fernando. Actas de las XVIII Jornadas de Programación y Lenguajes (PROLE 2018), 2018-09-17.This paper presents an on-going work that includes semantic analysis of SQL statements in the database system DES. Following Brass&Goldberg, SQL statements, while syntactically correct, can exhibit symptoms of bad design. By warning users about such symptoms, both the learning curve of students as well as productivity of SQL practitioners can be enhanced. Some errors include inconsistent conditions, lack of correlations in joins, unused tuple variables and the like. Here, we describe the semantic checker developed for DES, which applies several techniques. In particular, it applies abstraction with CLP solving, and specific algorithms for the different kind of errors. This proposal has been implemented in the deductive system DES and available at des.sourceforge.net. ResumenA Datalog Framework for Modeling Relationship-based Access Control PoliciesPasarella, Edelmira; Lobo, Jorge. Actas de las XVIII Jornadas de Programación y Lenguajes (PROLE 2018), 2018-09-17.Relationships like friendship to limit access to resources have been part of social network applications since their beginnings. Describing access control policies in terms of relationships is not particular to social networks and it arises naturally in many situations. Hence, we have recently seen several proposals formalizing different Relationship-based Access Control (ReBAC) models. In this paper, we introduce a class of Datalog programs suitable for modeling ReBAC and argue that this class of programs, that we called ReBAC Datalog policies, provides a very general framework to specify and implement ReBAC policies. To support our claim, we first formalize the merging of two recent proposals for modeling ReBAC, one based on hybrid logic and the other one based on path regular expressions. We present extensions to handle negative authorizations and temporal policies. We describe mechanism for policy analysis, and then discuss the feasibility of using Datalog-based systems as implementations. ResumenQL: Object-oriented Queries on Relational DataAvgustinov, Pavel; de Moor, Oege; Peyton Jones, Michael; Schäfer, Max. Actas de las XVIII Jornadas de Programación y Lenguajes (PROLE 2018), 2018-09-17.Paper already published at: European Conference on Object-Oriented Programming (ECOOP) 2016 This paper describes QL, a language for querying complex, potentially recursive data structures. QL compiles to Datalog and runs on a standard relational database, yet it provides familiar-looking object-oriented features such as classes and methods, reinterpreted in logical terms: classes are logical properties describing sets of values, subclassing is implication, and virtual calls are dispatched dynamically by considering the most specific classes containing the receiver. Furthermore, types in QL are prescriptive and actively influence program evaluation rather than just describing it. In combination, these features enable the development of concise queries based on reusable libraries, which are written in a purely declarative style, yet can be efficiently executed even on very large data sets. In particular, we have used QL to implement static analyses for various programming languages, which scale to millions of lines of code.