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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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Getting BCNF from a group of functional dependencies

Here is a group of FDs(3NF): A-> BDEFG CF->A BG->C How can I decompose this relation to BCNF? I guess there are still dependencies in CF->A because A->F, but have no idea how to decompose it.. Anyone can help please? Thanks!
Crystal
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Is my application of Boyce-Codd NF correct in this exercise?

EXAM revision, not homework. I'm working on this exercise and I would like to check is my solution okay: Given the following relationship, R, and set of functional dependencies, F: R = {A,B,C,D,E,F,G,H,I} F= { {C,D} -> {A}, {G} -> {E}, {C,D,E}…
chris loughnane
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Boyce-Codd Normal Form explain

Accoring to Boyce-Codd Normal Form Definition, Reln R with FDs F is in BCNF if, for all X -> A in F+ -A is subset of X (called a trivial FD), or -X is a superkey for R. “R is in BCNF if the only non-trivial FDs over R are key constraints.” If…
runcode
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Struggling with functional dependency practice questions

I'm going over some practice questions. F={ B→E, C→B, CD→E, ABE→C} I tried to make a canonical cover - Fc ={ B→E, C→B, D→E, AB→C} Then finding candidate keys - ADB, ADC Is R in BCNF? I thought it isn't in BCNF if I do not do lossless and…
Ofekino97
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Is this database 3NF or BCNF?

I have this table that the rules are: A student is examined in a discipline and obtains a position on the class list. It is known that two students cannot obtain the same position in the same subject. Is this a 3NF database or BCNF, i cant have a…
Young JooJ
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Converting 3NF to BCNF

I am trying to change my table from Third Normal Form to BCNF but not sure I understand the concept entirely. I managed to work through 1NF, 2NF and 3NF (I think), but need help getting it to BCNF. I have **Students Table** ID -- First Name --…
shanlikestrains
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What determinants do I have in my entity? Trying to understand BCNF

My teacher told me that if an entity is in BCNF all determinants should be a super key, but i'm struggling to understand this. I have an entity for a cinema database with following attributes: Showtime_id (PK), Date, Showtime, Hall. I understand…
sakura
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Normalization Form

would like to ask a question that related with normalization form. R = A,B,C,D AB -> CD CD -> AB Is this is 3NF with BCNF ? why ?
Yannis
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Dependency preservation, based of original functional dependencies or canonical cover?

Given these functional dependencies for R: {A,B,C,D,E,F} AC->EF E->CD C->ADEF BDF->ACD I got this as the canonical cover: E->C C->ADEF BF->C And then broke it down to Boyce Codd Normal Form: Relation 1: {C,A,D,E,F} Relation 2: {B,F,C} I…
Loqgar
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Is this in BCNF?

Assume that the relation is obtained through decomposition from a relation with attributes ABCDEFGHI and that dependencies over ABCDEFGHI are listed below. R(A,B,F) B->E A->F We need to convert this relation into BCNF What i have done till now…
sania00
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Is this a BCNF violation?

I read oodles of examples stating that 3NF is BCNF as long as there are no overlapping candidate keys... Given: R(a,b,c,d,e,f) a,b,c -> d a,b,c -> e a,b,c -> f so, a,b,c is the only candidate key. So far it's BCNF. Now, I add the FD f-> c ,…
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Convert Relation to 3rd Normal Form and BCNF Check Work

I am trying to convert this relation into 3rd Normal Form and BCNF. Given a relation R(A1, A2, A3, A4), with three FDs A2, A3 → A4 ; A3, A4 → A1; A1, A2→ A3. Provide the 3NF and BCNF form of the schema and explain why. I remember doing this but…
Srikar Murali
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BCNF decomposition --- Am I doing this wrong?

I am working on lossless-join decomposition on the relation R(A,B,C,D,E). The relation has functional dependencies: {A->BC,B->D,CD->E,E->A} (1) I think candidate keys are {A} and {E} (2) And BCNF violations are {B->D} and {CD->E}, because {B} and…
jetsai
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BCNF - Is it possible here? Name, Sport Centre, Sport

I'm trying to get a better understanding of normalisation so I can use best practices going forward. I've found a question in an old book and I'm a little confused by it. Essentially I'm given this table with the following data: Name Sport …
JamMan9
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Normalization. Looking for feedback on what should be 3NF

I am creating a database for a super market in my database class. The database needs to be at least 3nf but if possible, BCNF. Could someone let me know if this is satisfactory? I believe it is and I just want to make sure.
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