A guide to the SQL standard
Parallel computation with threshold functions
Journal of Computer and System Sciences - Structure in Complexity Theory Conference, June 2-5, 1986
Journal of Computer and System Sciences - 3rd Annual Conference on Structure in Complexity Theory, June 14–17, 1988
Converting nested algebra expressions into flat algebra expressions
ACM Transactions on Database Systems (TODS)
Low-complexity aggregation in GraphLog and Datalog
ICDT Selected papers of the 4th international conference on Database theory
Database systems: principles, programming, performance
Database systems: principles, programming, performance
On a monadic NP vs monadic co-NP
Information and Computation
Principles of programming with complex objects and collection types
ICDT '92 Selected papers of the fourth international conference on Database theory
Normal forms and conservative extension properties for query languages over collection types
Journal of Computer and System Sciences
Information and Computation
Counting quantifiers, successor relations, and logarithmic space
Journal of Computer and System Sciences - special issue on complexity theory
Journal of Computer and System Sciences - Special issue: 26th annual ACM symposium on the theory of computing & STOC'94, May 23–25, 1994, and second annual Europe an conference on computational learning theory (EuroCOLT'95), March 13–15, 1995
Query languages for bags and aggregate functions
Journal of Computer and System Sciences - Special issue on principles of database systems
Information and Computation - Special issue: logic and computational complexity
Equivalence of Relational Algebra and Relational Calculus Query Languages Having Aggregate Functions
Journal of the ACM (JACM)
Joe Celko's SQL for smarties: advanced SQL programming (2nd editor)
Joe Celko's SQL for smarties: advanced SQL programming (2nd editor)
Local properties of query languages
Theoretical Computer Science - Special issue on the 6th International Conference on Database Theory—ICDT '97
Logics with counting and local properties
ACM Transactions on Computational Logic (TOCL)
Locality of order-invariant first-order formulas
ACM Transactions on Computational Logic (TOCL)
Logics with aggregate operators
Journal of the ACM (JACM)
Foundations of Databases: The Logical Level
Foundations of Databases: The Logical Level
Universality of data retrieval languages
POPL '79 Proceedings of the 6th ACM SIGACT-SIGPLAN symposium on Principles of programming languages
On the Power of Aggregation in Relational Query Languages
DBLP-6 Proceedings of the 6th International Workshop on Database Programming Languages
On the Forms of Locality over Finite Models
LICS '97 Proceedings of the 12th Annual IEEE Symposium on Logic in Computer Science
Non-linear prefixes in query languages
Proceedings of the twenty-sixth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
On the expressibility of functions in XQuery fragments
Information Systems
Expressiveness and complexity of XML publishing transducers
ACM Transactions on Database Systems (TODS)
Database theory: query languages
Algorithms and theory of computation handbook
ACM Transactions on Information and System Security (TISSEC)
On the expressive power of XQuery fragments
DBPL'05 Proceedings of the 10th international conference on Database Programming Languages
Proceedings of the VLDB Endowment
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It is a folk result in database theory that SQL cannot express recursive queries such as reachability; in fact, a new construct was added to SQL3 to overcome this limitation. However, the evidence for this claim is usually given in the form of a reference to a proof that relational algebra cannot express such queries. SQL, on the other hand, in all its implementations has three features that fundamentally distinguish it from relational algebra: namely, grouping, arithmetic operations, and aggregation.In the past few years, most questions about the additional power provided by these features have been answered. This paper surveys those results, and presents new simple and self-contained proofs of the main results on the expressive power of SQL. Somewhat surprisingly, tiny differences in the language definition affect the results in a dramatic way: under some very natural assumptions, it can be proved that SQL cannot define recursive queries, no matter what aggregate functions and arithmetic operations are allowed. But relaxing these assumptions just a tiny bit makes the problem of proving expressivity botmds for SQL as hard as some long-standing open problems in complexity theory.