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Questions tagged [bcnf]

Boyce–Codd normal form (or BCNF or 3.5NF) is a normal form used in database normalisation.

Boyce–Codd normal form (or BCNF or 3.5NF) is a normal form used in database normalisation. It is a slightly stronger version of the third normal form (3NF). BCNF was developed in 1974 by Raymond F. Boyce and Edgar F. Codd to address certain types of anomaly not dealt with by 3NF as originally defined.

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Prime attribute and keys

Is a prime attribute only a member of candidate keys or can it also be superkeys? I am a bit confused as I am reading somewhere that a prime attribute can be a member of ANY key, and other says it needs to be a member of a Candidate key.
user7722505
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How to BCNF decompose when an attribute has no relation with any others

Assignment: Consider a relation (,,,,,,) and its FD set = { → , → , → , → , → , → }. Decompose it into a collection of BCNF relations if it is not in BCNF. Make sure your decomposition is lossless-join. Explanation Hi, I'm working on my…
Rong Chenxuan
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Check BCNF at movie database?

I am a bit confused how to check BCNF in a database diagram.I saw some youtube videos about what is database normalization (1NF,2NF...) but when the time comes to apply these rules to my project , i don't know what to do . My ER diagram for a movie…
Klainti
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Confusion over BCNF

Schema: R(A,B,C,D,E,F,G,H,I,J) and functional dependencies FD = { A->DE, IJ->H, I->A, J->FG, G->BC } Question: Is relation in BCNF? Answer: It's not because A is not superkey. I'm aware under which conditions relation is in BCNF, but what confuses…
sss
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Which of the following are true regarding 3NF and BCNF?

Suppose i have a table A which consists of only 1 candidate key then what is true ? If it is in 3NF, then it is also in BCNF or not ?
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Functional dependencies for a relation with all prime attributes?

I am doing a database theory course as part of my CS degree, and we have to confirm a database we designed is in BCNF. I am trying to create the functional dependencies, but I don't know what to do when a relation is all prime. (All attributes are…
Fishingfon
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Can BCNF only be violated when table contains more than one candidate key?

I read in a book : "BCNF can be violated only when table contains more than one candidate key." Consider the following example: Sn Rollno Name Game 1 u11co098 Robert Basketball 2 u11ce034 Bob Cricket 3 u11co098 Robert …
Maverick
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Boyce codd normal form

I have the following relationship: R(W, X, Y, Z) X->Y X->Z I have to decompose it into BCNF. I don't understand how I'm supposed to go about doing this as I have no information about W. I've been searching online for the past 2 hours trying to find…
Collin
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Is this allowed in BCNF Normalization?

I know that in BCNF if A->B then A must be a candidate key. But what about if A is part of the candidate key but not the whole candidate key? Let me explain in an example: Exercise 1: Candidate keys: {A},{B,C} Functional dependencies: B->D Relation:…
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Is it ok to create a new database table for each metric?

My engineering team builds a machine and records various metrics related to the machine such as battery voltage, name of the machine, number of times used etc. My current database structure has the following columns in one table ID Name of the…
user1048278
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When does BCNF not preserve functional dependencies, and should I then use 3NF?

When is BCNF not able to preserve functional dependencies? When is a 3NF decomposition desired instead of a BCNF decomposition preserving functional dependencies? Please explain with an example. I saw this question but it does not answer my…
Durgesh Singh
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Why don't we decompose all relations into 2-attribute relations?

Relations having only 2 attributes are in BCNF. Why don't we decompose all relations into 2-attribute relations? Because if we do so, we cannot achieve lossless join. What is an example of decomposing a relation into 2-attribute relations where…
Triet Doan
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prime to prime transitivity in 3nf normal form

I am stuck in this question. What should be the answer to this: The relation scheme Student Performance (name, courseNo, rolINo, grade) has the following functional dependencies: name, courseNo, -> grade rolINo, courseNo -> grade …
Mehul Jain
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A short summary of what BCNF is?

For my exam I am revising for in January I will need to know all about Boyce-Codd Normal Form and possibly have to write a short summary about what it is. In a paragraph or so, what exactly is BCNF as I have looked on many sites and the…
Michael
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Does City and Zip in Address Table Violate BCNF

Let's say you have a the following --------------------------- attribute constraints | -------- ----------- | id (PK) | location_name ** | street | zipcode | city ** realistically Unique,…
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