Introduction: Dr. LING Tok Wang is a professor of the Department of Computer Science, School of Computing at the National University of Singapore. He was the Head of IT Division, Deputy Head of the Department of Information Systems and Computer Science, and Vice Dean of the School of Computing of the University. Before joining the University as a lecturer in 1979, he was a scientific staff at Bell Northern Research, Ottawa, Canada. He received his Ph.D. and M.Math., both in Computer Science, from University of Waterloo (Canada) and B.Sc.(1st class Hons) in Mathematics from Nanyang University (Singapore). His research interests include Data Modeling, Entity-Relationship Approach, Object-Oriented Data Model, Normalization Theory, Logic and Database, Integrity Constraint Checking, Semi-Structured Data Model, XML Twig Pattern Query Processing, ORA-semantics based XML and Relational Database Keyword Query Processing. He has published more than 230 international journal/conference papers and chapters in books, all in database research areas. He also co-edited 13 conference and workshop proceedings, co-authored one book, and edited one book. He is an ER Fellow, an ACM Distinguished Scientist, IEEE Senior Life Member, and Senior Member of Singapore Computer Society. He received the ACM Recognition of Service Award in 2007, the DASFAA Outstanding Contributions Award in 2010, and the Peter P. Chen Award in 2011.