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ICDE
2004
IEEE
89views Database» more  ICDE 2004»
14 years 5 months ago
Nested Queries and Quantifiers in an Ordered Context
We present algebraic equivalences that allow to unnest nested algebraic expressions for order-preserving algebraic operators. We illustrate how these equivalences can be applied s...
Norman May, Sven Helmer, Guido Moerkotte
ICDT
2010
ACM
161views Database» more  ICDT 2010»
14 years 1 months ago
Composition with Target Constraints
It is known that the composition of schema mappings, each specified by source-to-target tgds (st-tgds), can be specified by a secondorder tgd (SO tgd). We consider the question of...
Marcelo Arenas, Ronald Fagin, Alan Nash
ICDE
1995
IEEE
164views Database» more  ICDE 1995»
14 years 5 months ago
Efficient Processing of Nested Fuzzy SQL Queries
?In a fuzzy relational database where a relation is a fuzzy set of tuples and ill-known data are represented by possibility distributions, nested fuzzy queries can be expressed in ...
Qi Yang, Chengwen Liu, Jing Wu, Clement T. Yu, Son...
ICDE
2007
IEEE
117views Database» more  ICDE 2007»
14 years 5 months ago
Unnesting Scalar SQL Queries in the Presence of Disjunction
Optimizing nested queries is an intricate problem. It becomes even harder if in a nested query the linking predicate or the correlation predicate occurs disjunctively. We present ...
Matthias Brantner, Norman May, Guido Moerkotte
IEEECSA
2009
13 years 1 months ago
Improved Query Plans for Unnesting Nested SQL Queries
- The SQL language allows users to express queries that have nested subqueries in them. Optimization of nested queries has received considerable attention over the last few years. ...
Pranav Khaitan, Satish Kumar M, Korra Sathya Babu,...