Recent questions tagged database-normalization

+2 votes

2 answers

1

UGCNET-June-2019-II-34
In relational databases, if relation R is in BCNF, then which of the following is true about relation R? R is in 4NF R is not in 1NF R is in 2NF and not in 3NF R is in 2NF and 3NF

asked Jul 2 in Databases by Arjun Veteran (424k points) | 280 views

+1 vote

3 answers

2

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 (9.7k points) | 225 views

+1 vote

2 answers

3

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 (117k points) | 186 views

0 votes

1 answer

4

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) | 79 views

0 votes

2 answers

5

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 (5.1k points) | 184 views

0 votes

1 answer

6

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 Junior (729 points) | 37 views

0 votes

2 answers

7

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) | 146 views

+1 vote

2 answers

8

#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 (259 points) | 166 views

0 votes

1 answer

9

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 (181 points) | 88 views

0 votes

1 answer

10

MadeEasy Workbook: Databases - Database Normalization

asked Jan 23 in Databases by Jyoti Kumari97 (181 points) | 79 views

0 votes

1 answer

11

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 (339 points) | 77 views

0 votes

0 answers

12

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 (1.3k points) | 38 views

0 votes

1 answer

13

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 Junior (521 points) | 75 views

0 votes

0 answers

14

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 (423 points) | 83 views

0 votes

0 answers

15

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) | 27 views

0 votes

1 answer

16

Ace 2019
Dependency preserving/Lossless ?

asked Jan 9 in Databases by balchandar reddy san Active (3.2k points) | 87 views

+1 vote

1 answer

17

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 (10.6k points) | 164 views

+1 vote

1 answer

18

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 (7.3k points) | 92 views

0 votes

0 answers

19

GA_Testseries
is this in 3NF?

asked Dec 10, 2018 in Databases by aditi19 Active (5.1k points) | 111 views

0 votes

0 answers

20

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 (5.1k points) | 82 views

+1 vote

0 answers

21

GA_Testseries

asked Dec 10, 2018 in Databases by aditi19 Active (5.1k points) | 50 views

+1 vote

1 answer

22

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 (279 points) | 95 views

0 votes

0 answers

23

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 (3.2k points) | 35 views

+2 votes

1 answer

24

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 (5.1k points) | 165 views

+1 vote

1 answer

25

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 (27.6k points) | 177 views

0 votes

1 answer

26

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 Veteran (54.7k points) | 274 views

0 votes

0 answers

27

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 (1.3k points) | 89 views

0 votes

1 answer

28

NORMALIZATION
The Highest Normal Form of the Following Relation? R(ABCDE) FD={AB$\rightarrow$C,DE$\rightarrow$C,B$\rightarrow$D} EDIT :- Decompose it into BCNF if possible

asked Nov 19, 2018 in Databases by Kshitij Hansda (123 points) | 138 views

0 votes

0 answers

29

#Self Doubt
In definition of transitive dependency we use conditions as A → B It is not the case that B → A B → C I am not able to understand why we need condition 2 for this ?

asked Nov 6, 2018 in Databases by Rameesh (435 points) | 139 views

+1 vote

1 answer

30

#Functional Depencency
max number of FD in a relation with 'n' attributes=$2^{2n}$ how this formula is obtained?

asked Oct 28, 2018 in Databases by aditi19 Active (5.1k points) | 74 views

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