'Dependency preserving' presentation slideshows

Carnegie Mellon Univ. Dept. of Computer Science 15-415/615 - DB Applications

1.61k views • 71 slides

Carnegie Mellon Univ. Dept. of Computer Science 15-415/615 - DB Applications

796 views • 71 slides

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Chapter 7: Relational Database Design

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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

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Database Design Theory

Database Design Theory. Which tables to have in a database Normalization. Database Design Theory. Given some body of data to be represented in a database, as modelled in an E-R diagram, what is the most suitable logical structure for that data?

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Schema Refinement and Normal Forms

Schema Refinement and Normal Forms. Chapter 19. Schema Refinement : Normal Forms. Question : How decide if any refinement of schema is needed ? If a relation is in a certain normal (good) form like BCNF, 3NF, etc.

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Functional Dependencies and Normalization

Functional Dependencies and Normalization. R&G Chapter 19 Lecture 26. Science is the knowledge of consequences, and dependence of one fact upon another. Thomas Hobbes (1588-1679 ). Administrivia. Homework 5 available Due a week from next Tuesday Final exam 4 weeks from yesterday.

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Dependency Preserving Decomposition

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Dependency Preserving Decomposition

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Schema Refinement and Normalization

Schema Refinement and Normalization. Nobody realizes that some people expend tremendous energy merely to be normal. Albert Camus . Functional Dependencies (FDs) (Review). A functional dependency X ? Y holds over relation schema R if, for every allowable instance r of R:

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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 )

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Schema Refinement and Normalization

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Normalization

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ICS 421 Spring 2010 Normal Forms

ICS 421 Spring 2010 Normal Forms. Asst. Prof. Lipyeow Lim Information & Computer Science Department University of Hawaii at Manoa. Two More Rules. Union If X ? Y and X ? Z , then X ? YZ Eg . FLD ? A and FLD ? T, then FLD ? AT Decomposition If X ? YZ , then X ? Y and X ? Z

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Normalization DB Tuning

Normalization DB Tuning. CS186 Final Review Session. Plan. Functional Dependencies, Rules of Inference Candidate Keys Normal forms (BCNF/3NF) Decomposition BCNF Lossless Dependency preserving 3NF + Minimal cover. Functional Dependencies.

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Normalization- 3NF

Normalization- 3NF. Instructor: Mohamed Eltabakh meltabakh@cs.wpi.edu. Part III. Announcements. Homework 2 is due NOW !!! Homework 3 will be out today (Nov. 15) and due on Nov. 22, 8:00AM Midterm on Nov. 22 Until Normalization (Normalization is included)

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THIRD NORMAL FORM (3NF)

THIRD NORMAL FORM (3NF). A relation R is in BCNF if whenever a FD X ?A holds in R, one of the following statements is true: X?A is a trivial FD, or X is a superkey, or A is part of some key. Why 3NF? .

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Theoretical Aspects of Normalization

Theoretical Aspects of 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 )

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Decompositions

Decompositions. Given a relation schema R that is not in 3NF (or perhaps BCNF) decomposition can be used to help fix this problem Decomposition replaces R with R1,...,RN where 1) attributes of Ri are a subset of the attributes of R 2) each attribute of R is in at least one Ri

263 views • 10 slides