Recent questions tagged database-normalization

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Doubt on database normalization for relation having all prime attributes
In a relation, if every attribute is prime but key may not be simple then the relation is in ______. A. 1NF B. 2NF C. 3NF D. BCNF

asked May 27 in Databases by Tuhin Dutta Loyal (9k points) | 94 views

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Made Easy Test Series: Database-Normalization
Consider the relation $R\left ( A,B,C,D,E \right )$ with functional dependencies $F=${ $A\rightarrow B$ $BC\rightarrow E$ $ED\rightarrow A$ } Number of additional relation required to convert it into lossless , dependency preserving $3NF$ decomposition is _____________ What is meaning of additional relation (Here no table mentioned previously)??

asked May 19 in Databases by srestha Veteran (111k points) | 69 views

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dbms normalization - 2nf/bcnf query
Consider the following relational schemes: R(A, B, C, D, E, F) and S(A, B, C) with in the following functional dependencies: I. AB --> C II. C --> ABDE III. ADE --> F Assume {A,B} is the key for both schemes. Which of the ... C is the relation for the S table, which satisfies BCNF properties. (So S is in BCNF) Please let me know if it is correct or not.

asked May 10 in Databases by pritam946 (9 points) | 33 views

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Molina Exercise-3.3 BCNF decomposition
Decompose into BCNF R(A, B, C, D, E) FD: AB->C, C->D, D>B, D->E

asked Apr 14 in Databases by aditi19 Active (3.7k points) | 111 views

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self-doubt
Consider 2 tables R1 and R2 . If we perform a cross product between them the condition that should be satisfied for not generating spurious tuples is both should have a common element which should be a 1>primary key 2>candidate key 3>super key In one of the tables which of the three is correct??

asked Mar 19 in Databases by Doraemon (179 points) | 19 views

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Gate: Normalization
Consider a relation $R (A, B, C, D, E, F, G, H) $ where each attribute is atomic, and following functional dependencies exist. Following relation is in $1 NF, $ I help me to decompose relation into $BCNF$ $CH\rightarrow G$ $A\rightarrow BC$ $B\rightarrow CFH$ $E \rightarrow A$ $F\rightarrow EG$

asked Feb 11 in Databases by anusuccess (5 points) | 96 views

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#MadeEasyTestSeries
S: If a relation R is in 3NF but not in BCNF then relation R must consist atleast 2 overlapped candidate keys. True/False

asked Jan 28 in Databases by Reshu $ingh (253 points) | 101 views

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MadeEasy Workbook: Databases - Database Normalization
Find the highest normal form. AB - - > CE E - - >AB C-->D Doubt AB, E are the candidate key. The answer given is 2NF In 2NF, there should be no partial dependency which is PRIME ATTRIBUTE - - >NON PRIME ATTRIBUTE But it is there in AB-->CE, I think CE is non prime attribute. Or bcoz of E we consider them as prime attribute.

asked Jan 25 in Databases by Jyoti Kumari97 (175 points) | 58 views

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MadeEasy Workbook: Databases - Database Normalization

asked Jan 23 in Databases by Jyoti Kumari97 (175 points) | 54 views

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Normal forms
Select the ‘False’ statement from the following statements about Normal Forms: 1. BCNF is stronger than 3NF 2. Lossless preserving decomposition into BCNF is always possible 3. Any Relation with two attributes is in BCNF 4. Lossless preserving decomposition into 3NF is always possible

asked Jan 21 in Databases by Hardik Vagadia (311 points) | 53 views

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self doubt - NO. of tables after normalizing
Are 3NF decompostions and BCNF decompostions unique? Are 4NF important for GATE (since I've left them :( ) See, I am asking this question because I want to know whether they'll ask about no. of tables we get after normalizing upto 3nf or bcnf. Now ... I am in a bit hurry to search for that.. so please forgive me if it has been already asked.) Thank you.

asked Jan 21 in Databases by Harsh Kumar Active (1.2k points) | 24 views

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GATE 1997-2.7 Small change in given data
Consider the schema R = (S T U V) and the dependencies S → T, T → U, U → V and V → S. Let R = (R1 and R2) be a decomposition such that R1 ∩ R2 = ϕ. (In the actual gate question it was R1∩R2 ≠ ϕ) The decomposition is:- not in 2NF in 2NF but not 3NF in 3NF but not in 2NF in both 2NF and 3NF

asked Jan 21 in Databases by Sukhbir Singh (317 points) | 31 views

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MadeEasy Test Series 2019: Databases - Database Normalization
A3 also deriving {A1,A2,A3} from FD’s...why it is still neglecting BCNF? Is solution wrong or I am misunderstanding?

asked Jan 20 in Databases by Naveen Muralidhar (373 points) | 49 views

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Ace Material
Business Rules : An employee may work in many departments. Each employee has a unique employee number. Each departments has many managers. An employee has only one manager for each department Each manager can manage only one department. Each employee has only one Name. ... HOW? NOTE : according to the solution eid should be the primary key. BUT how can you find manager with only eid?

asked Jan 17 in Databases by OneZero Active (2.1k points) | 17 views

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Ace 2019
Dependency preserving/Lossless ?

asked Jan 9 in Databases by balchandar reddy san Active (3k points) | 64 views

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MadeEasy Test Series: Databases - Database Normalization
Consider a database with the following relation: Shipping (ShipName, ShipType, TripId, Cargo, Port. Date) With the following functional dependencies: sorry for not typing ,i will type it later my doubt is-isn’t partial dependency $ShipName\rightarrow ShipType$ present in new database??

asked Jan 5 in Databases by Prateek Raghuvanshi Boss (10.1k points) | 114 views

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Number of tables required
E and F are multivalued attributes. How many minimum tables which satisfy 1NF ? How many minimum tables which satisfy 2NF ? How many minimum tables which satisfy 3NF ? How many minimum tables which satisfy BCNF ?

asked Jan 1 in Databases by Rishav Kumar Singh Loyal (5.4k points) | 56 views

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18

No. Of tables
The number of tables required in SELF-REFERENTIAL relation when different mappings(1: M, M:1, 1:1, M: N) are used with different participation (Partial Participation at both sides, Total Participation at both sides and partial participation at one side).

asked Jan 1 in Databases by Rishav Kumar Singh Loyal (5.4k points) | 28 views

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Testbook Test Series: Databases - Database Normalization
The number of tables required to convert the relational schema $R(A, B, C, D, E, F, G, H)$ into $3NF$ with following functional dependency is ________ $A\rightarrow DG$ $AB\rightarrow E$ $D\rightarrow C$ $E\rightarrow F$ $G\rightarrow H$

asked Dec 27, 2018 in Databases by jatin khachane 1 Loyal (6.7k points) | 70 views

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Normalization, Made easy practice book
I think the ans should be (b), but it is given (a)

asked Dec 12, 2018 in Databases by Harsh Kumar Active (1.2k points) | 60 views

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21

GA_Testseries
is this in 3NF?

asked Dec 10, 2018 in Databases by aditi19 Active (3.7k points) | 96 views

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GA_Testseries
is option B correct? in ii) intersection of the two normalized relation is EF which is not key of either of the relations how can option B be correct?

asked Dec 10, 2018 in Databases by aditi19 Active (3.7k points) | 66 views

+1 vote

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23

GA_Testseries

asked Dec 10, 2018 in Databases by aditi19 Active (3.7k points) | 39 views

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24

Self doubt dbms Normalisation
Is minimal set of functional dependency for a functional dependency set is always unique???

asked Dec 10, 2018 in Databases by gatecrack (221 points) | 79 views

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25

previous
https://gateoverflow.in/3767/gate2005-it-22 It isn’t mentioned that the fields are atomic then how could answer be 1NF?

asked Dec 9, 2018 in Databases by Shivam Kasat Active (3k points) | 27 views

+2 votes

1 answer

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Raghuramkrishnan
R(A, B, C, D) FD: B->C, D->A is the following decomposition in BCNF? R1(B, C), R2(A, D), R3(C, D)

asked Nov 29, 2018 in Databases by aditi19 Active (3.7k points) | 133 views

+1 vote

1 answer

27

Relation Decomposition
Decompose below relation into 2NF,3NF and BCNF with lossless join and Dependency Preserving. $R(ABCDE)$ $F=\{AB\rightarrow C,DE \rightarrow C,B \rightarrow D\}$ According to my analysis The only key here is $ABE$ ... $R_3(CDE) \{DE \rightarrow C\}$ And All three above are in BCNF as well. Is my decomposition correct?

asked Nov 28, 2018 in Databases by Ayush Upadhyaya Boss (24.6k points) | 124 views

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28

Functional preserving
Given $R(A,B,C,D,E)$ and $F:\left \{A\rightarrow BC ,CD\rightarrow E,B\rightarrow D,E\rightarrow A\right \}$,Decompose into $BCNF?$ $(a)$Every $BCNF$ is $3NF$ and vice versa $?$ $(b)FD$ preserving or not$?$ $(c)$ Lossless decomposition or lossy decomposition?

asked Nov 20, 2018 in Databases by Lakshman Patel RJIT Boss (39.7k points) | 242 views

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29

Self-doubt [Foreign keys and Third Normal Form]
I've some elementary doubts regarding Foreign keys (referential integrity) : Can a foreign key consist of a collection of attributes - ie. can two or more columns collectively form a foreign key? If foreign key refers ... : Multiple candidate keys Composite candidate keys Overlapping candidate keys If possible, please provide an example. Thank You.!

asked Nov 19, 2018 in Databases by Harsh Kumar Active (1.2k points) | 67 views

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