Since December 2015, I am the editor of the Database Principles Column of SIGMOD Record which publishes surveys of recent results that appear in database theory publications (such as ACM PODS or ICDT) in a form suitable for a larger audience. Leonid Libkin edited the colum since its inception in 1999 until June 2011, while Pablo Barcelo took over from June 2011 until December 2015. Some of the best database theoreticians (and not only database theoreticians) contributed  papers on many different aspects of databases. All of the papers published in the column can be found here.

Serge Abiteboul
   On views and XML (pdf)

Guozhu Dong, Juanwen Su
    Incremental Maintenance of Recursive Views Using Relational Calculus/SQL (ps)

Jan Van den Bussche
    Constraint Databases: A Tutorial Introduction (pdf)

Alon Halevy
    Theory of Answering Queries Using Views (pdf) 

Peter Buneman, Wenfei Fan, Jerome Simeon, Scott Weinstein
    Constraints for Semi-structured Data and XML (ps)

Luca Cardelli
    Describing Semistructured Data (pdf)

Dan Suciu
    The XML Typechecking Problem (ps)

Ronald Fagin
    Combining Fuzzy Information: an Overview (ps)

Frank Neven
    Automata theory for XML researchers (pdf)

Martin Grohe
    Parameterized Complexity for the Database Theorist (pdf)

Victor Vianu
    From Codd to XML (ps)

Diego Calvanese, Giuseppe De Giacomo, Maurizio Lenzerini, Moshe Vardi
    Regular path queries (pdf)

Thomas Schwentick
    XPath Query Containment (pdf)

Georg Gottlob, Christoph Koch
    Logic-based Web Information Extraction (pdf)

Sara Cohen
     Containment of Aggregate Queries (pdf)

Rick Hull, Jianwen Su
     Tools for Composite Web Services: A Short Overview (pdf)

Francesco Scarcello
     Query Answering Exploiting Structural Properties (pdf)

Alin Deutsch, Lucian Popa, Val Tannen
     Query Reformulation with Constraints (pdf)

Leopoldo Bertossi
     Consistent Query Answering in Databases (pdf)

Marcelo Arenas
     Normalization Theory for XML (pdf)

Luc Segoufin
     Static Analysis of XML Processing with Data Values (pdf)

Wim Martens,   Frank Neven,   Thomas Schwentick
     Simple off the shelf abstractions for XML schema (pdf)

Maarten Marx, Balder ten Cate
     Navigational XPath: calculus and algebra (pdf)

Christoph Koch
     On Query Algebras for Probabilistic Databases (pdf)

Benny Kimelfeld, Yehoshua Sagiv
     Modeling and Querying Probabilistic XML Data (pdf)

Pablo Barcelo
     Logical Foundations of Relational Data Exchange (pdf)

Nicole Schweikardt
     Machine Models for Query Processing (pdf)

Marcelo Arenas, Jorge Perez, Juan Reutter, Cristian Riveros
     Composition and Inversion of Schema Mappings (pdf)

Daniel Deutsch, Tova Milo
     On Models and Query Languages for Probabilistic Processes (pdf)

Andrea Cali, Georg Gottlob, Thomas Lukasiewicz, Andreas Pieris
     A Logical Toolbox for Ontological Reasoning (pdf)

Peter Wood
     Query Languages for Graph Databases (pdf)

Mikolaj Bojanczyk
     Algorithms for Regular Languages that Use Algebra (pdf)

Grigoris Karvounarakis, Todd J. Green
     Semiring-Annotated Data: Queries and Provenance Algebras (pdf)

Marcelo Arenas, Claudio Gutierrez, Daniel Miranker, Jorge Perez, Juan Sequeda
     Querying Semantic Data on the Web (pdf)

Graham Cormode
     The Continuous Distributed Monitoring Model (pdf)

Jan Chomicki, Paolo Ciaccia, Niccolo Meneghetti
     Skyline Queries, Front and Back (pdf)

Hung Q. Ngo, Christopher Re, Atri Rudra
     Skew Strikes Back: New Developments in the Theory of Join Algorithms (pdf)

Andrew Mcgregor.
     Graph Streams Algorithms: A Survey (pdf)

Tom Ameloot
     Declarative Networking: Recent Theoretical Work on Coordination, Correctness, and Declarative Semantics (pdf)

Alin Deutsch, Rick Hull, Victor Vianu
     Automatic Verification of Database-Centric Systems (pdf)

Yael Amsterdamer, Tova Milo
     Foundations of Crowd Data Sourcing (pdf)

Luc Segoufin
     Constant Delay Enumeration for Conjunctive Queries (pdf)

Wenfei Fan
     Data Quality: From Theory to Practice (pdf)

Ron Fagin, Benny Kimelfeld, Frederick Reiss, Stijn Vansummeren
     A Relational Framework for Information Extraction (pdf)