6th Intl. Workshop on Foundations of
Models and Languages for Data and Objects (FMLDO'96),
University of Magdeburg, Faculty of Computer Science,
Preprint No. 4, 1996,
Towards a Logical Semantics for Referential Actions in SQL
Bertram Ludäscher, Wolfgang May, Joachim Reinert
We investigate a logical semantics which
unambiguously specifies the meaning of SQL-like referential actions of
the form ON DELETE CASCADE and ON DELETE RESTRICT. The semantics is
given by a translation of referential actions into logical rules. The
proposed semantics is less restrictive than the standard SQL
semantics, yet preserves all referential integrity constraints.
First, a preliminary set of rules is introduced which rejects a set of
user requests if a single request is rejected. Subsequently, a
refined translation is presented using Statelog, a
state-oriented Datalog extension which allows to define active and
deductive rules within a unified framework. We show that our semantics
yields the maximal admissible subset of a given set of user requests.
Apart from the Statelog formalization, a three-valued formalization
based on the well-founded semantics and an equivalent game-theoretic
specification are presented, which give further insight into the
problem of ambiguity of triggers.
[Slides of the talk]
Followup papers have been published in
and TODS 27(4), 2002.
An extended version containing these results can be found in
the Global Semantics of Referential Actions using
Wolfgang May, Bertram Ludäscher,
ACM Transactions on Database Systems (TODS), 27(4), 2002.