Browsing by Author "Lee M L"

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    Extending Classical Functional Dependencies for Phsical Database Design
    (1994-05-01T00:00:00Z) Ling T W; Goh C H; Lee M L
    Traditionally, database design activities are partitioned into distinct phases in which a logical design phase precedes physical database design. The objective of the logical design step is to eliminate redundancies and updating anomalies using the notion of data dependencies, while leaving the physical design step to consider how the database schema may be restructured to provide more efficient access. We argue in this paper that the separation of these two steps often result in physical database design not being able to benefit from knowledge of the semantics of data captured in the earlier phases of the database design life cycle. As a step towards overcoming this problem, we demonstrate how classical functional dependencies can be extended to capture data semantics relevant to the design of database schemas which are more desirable from the efficiency point of view. This is accomplished via the introduction of strong and weak functional dependencies, as well as three new formal forms --- the relaxed 3NF, replicated 3NF and relax-replicated 3NF --- induced by the extended functional dependencies. These new normal forms provide a framework for designing database schemas which are more efficient, while not compromising the integrity of the underlying database.
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    View Update in Entity-Relationship Based Database Management Systems
    (1992-02-01T00:00:00Z) Ling T W; Lee M L
    Abstract not available.