Database System Concepts
7th Edition
ISBN: 9780078022159
Author: Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher: McGraw-Hill Education
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Expert Solution & Answer
Chapter 7, Problem 36E
Explanation of Solution
BCNF (Boyce Codd Normal Form):
A relation is said to be in BCNF if it holds the following 2 conditions:
- The relation is in Third Normal Form
- For every dependency X→a, X is superkey.
Every binary relation which means every schema consisting of exactly 2 attributes is said to be in BCNF.
In order to prove that, consider all possible combinations of functional dependencies on a relation R with 2 attributes A1 and A2.
Case1: A1→A2
In this case, A1 is the candidate key and hence also a superkey as candidate keys is minimal superkeys.
So, the BCNF condition satisfies in this case...
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Students have asked these similar questions
It is possible to have a schema and a decomposition that were not produced by the process, are in BCNF, and are not lossless despite the BCNF method's assurance of lossless decomposition. Describe how a schema like this is broken down and provide an example.
Consider the schema R = (A, B, C, D, E, G) and the set F of functional dependencies:A → BCBD → ECD → AB For your decomposition, state whether it is dependency preserving and explain why ?
Should the cardinality between entities be translated/read from both ends of the notation when dealing with database entity relationship modeling?
To put it another way, can a connection between two things be comprehended by reading it both forward and backward?
Chapter 7 Solutions
Database System Concepts
Ch. 7 - Prob. 1PECh. 7 - Prob. 2PECh. 7 - Explain how functional dependencies can be used to...Ch. 7 - Prob. 4PECh. 7 - Prob. 5PECh. 7 - Prob. 6PECh. 7 - Prob. 7PECh. 7 - Prob. 8PECh. 7 - Prob. 9PECh. 7 - Prob. 10PE
Ch. 7 - Prob. 11PECh. 7 - Prob. 12PECh. 7 - Prob. 13PECh. 7 - Prob. 14PECh. 7 - Prob. 15PECh. 7 - Prob. 16PECh. 7 - Prob. 17PECh. 7 - Prob. 18PECh. 7 - Prob. 19PECh. 7 - Prob. 20PECh. 7 - Prob. 21ECh. 7 - Prob. 22ECh. 7 -
Explain what is meant by repetition of...Ch. 7 -
Why are certain functional dependencies called...Ch. 7 - Prob. 25ECh. 7 - Prob. 26ECh. 7 - Prob. 27ECh. 7 - Prob. 28ECh. 7 - Prob. 29ECh. 7 - Prob. 30ECh. 7 - Prob. 32ECh. 7 - Prob. 33ECh. 7 - Prob. 35ECh. 7 - Prob. 36ECh. 7 - Prob. 37ECh. 7 - Prob. 38ECh. 7 - Prob. 39ECh. 7 - Prob. 40ECh. 7 - Prob. 41ECh. 7 - Prob. 42ECh. 7 - Prob. 43E
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- Consider a relation with schema R(A,B,C,D,E,F,G). Choose the key for the relation for the following sets of functional dependencies. BCD→A BC→E A→F F→ G C→ D A→ G ? A) B B) C C) BC D) All combinations of attributes are keyarrow_forwardInstead of the snowflake model, write about the pros and cons of the star schema. Which is more unusual?arrow_forwardEstablish the IoT reference model and explain it. The reference model has four distinct degrees of dependency.arrow_forward
- Instead of the snowflake model, write about the pros and cons of the star schema. Which one deviates more?arrow_forwardShould the cardinality between entities be translated/read from both ends of the notation when dealing with database entity relationship modelling? In other words, should a relationship between things be understandable when read both forwards and backwards?arrow_forwardConsider a schema R={A,B,C,D,E} and the following set of functional dependencies: {AB-> C, C->D, D->BE} Is R in Boyce-Codd normal form? Justify your answer.arrow_forward
- Transform an entity-relationship (E-R) diagraminto an equivalent set of well-structured(normalized) relations.arrow_forwardWhat are the key distinctions between a straightforward multivalued attribute and a repeating group?arrow_forwardAn ID-dependent Weak Entity typically result in a table with a compound primary key with at least one part of the PK also being a foreign key T or Farrow_forward
- A weak entity set may always be made stronger by adding the primary-key attributes of its identifying entity set to its attributes. Give an example of the kind of redundancy that will come from our choices.arrow_forwardEvery flimsy entity set may be strengthened by the addition of pertinent characteristics. What therefore, is the cause of our subpar entity sets?arrow_forwardLet R be a relational schema with attributes {M, N, O, P, Q, R} and let F be the set of functional dependencies F = {MN→OP, O→Q, QR→N, R→P}. Prove whether R is in 3NF.arrow_forward
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