AN EXTENDED RELATIONAL DATA MODEL AND SQL SUBSET WITH SUPPORT FOR CONTAINMENT, COMPOSITE STRUCTURES AND INHERITANCE
Date
1996-12-01
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Abstract
An extended relational data base model and SQL subset is described. The
data model is fully relational. It allows unnormalized relations only where
attributes are sets or lists of atomic attributes. There is support for
both inheritance and composite entities. A composite structre can be
stored by decomposition into sets of tuples stores in relations but can
also be stored virtually as a view. Composite structures, including OOPL
objects, can be transferred directly between database system and program
variables. Manipulation languages are an extended SQL and a separate new
SQL language subset for efficient manipulation of containment structures,
whose manipulation with SQL is error-prone. The language subset has a
predicate calculus expression structure, but allows the use of genitive
relations to model containment relationships and facilitate application
of natural quantifiers to containment sets. Range variables are allowed
and can range over genitive relations as well as base tables.
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Computer Science