'Qty value' diaporamas de présentation

Schema Refinement and Normal Forms

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Schema Refinement and Normal Forms

Schema Refinement and Normal Forms. The Evils of Redundancy. Redundancy is at the root of several problems associated with relational schemas: redundant storage, insert/delete/update anomalies

453 views • 30 slides

Schema Refinement and Normal Forms

Schema Refinement and Normal Forms. Chapter 19. The Evils of Redundancy. Redundancy is at the root of several problems associated with relational schemas: redundant storage, insert/delete/update anomalies

412 views • 25 slides

Functional Dependencies, BCNF and Normalization

Functional Dependencies, BCNF and Normalization. Functional Dependencies (FDs). A functional dependency X Y holds over relation R if, for every allowable instance r of R: t1 r, t2 r, ( t1 ) = ( t2 ) implies ( t1 ) = ( t2 )

450 views • 25 slides