Recent questions tagged database-normalization

+2 votes

6 answers

1

ISRO2020-50
If every non-key attribute functionally dependent on the primary key, then the relation will be in First normal form Second normal form Third normal form Fourth Normal form

asked Jan 13 in Databases by Satbir Boss (23.9k points) | 421 views

0 votes

0 answers

2

KPGCET-CSE-2019-74
The multivalued dependencies (MVDs) can be eliminated using ______ normal form on _____ normal form relations. $1$st, $2$nd $2$nd, $3$rd $3$rd, BCNF $4$th, BCNF

asked Aug 4, 2019 in Others by gatecse Boss (17.5k points) | 14 views

+3 votes

4 answers

3

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, 2019 in Databases by Arjun Veteran (431k points) | 336 views

+1 vote

3 answers

4

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, 2019 in Databases by Tuhin Dutta Boss (10.6k points) | 263 views

+1 vote

2 answers

5

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, 2019 in Databases by srestha Veteran (119k points) | 215 views

0 votes

1 answer

6

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, 2019 in Databases by pritam946 (9 points) | 93 views

+1 vote

3 answers

7

Made Easy Test Series:DBMS-Functional Dependency
Consider a relation $R\left ( A,B,C,D,E \right )$ and functional dependencies are $F=\left \{ AC\rightarrow B,C\rightarrow D,A\rightarrow E,C\rightarrow B \right \}$ Relation $R$ ... Then Is it a lossless decomposition? I am getting doubt, how it can be not lossless decomposition?

asked Apr 28, 2019 in Databases by srestha Veteran (119k points) | 135 views

0 votes

2 answers

8

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, 2019 in Databases by aditi19 Active (5.2k points) | 209 views

0 votes

1 answer

9

made easy test series - lossless join and dependency preserving
How is A answer?

asked Apr 7, 2019 in Databases by amitqy Active (1.9k points) | 111 views

0 votes

0 answers

10

Doubt
Do we need to find closure of functional dependencies of original relation to check whether the decomposed tables are in 2NF . I know that we have to do the above process for 3NF and BCNF . If yes , please give a example where we need to do it

asked Mar 30, 2019 in Databases by ashunimbz (59 points) | 17 views

0 votes

1 answer

11

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, 2019 in Databases by Doraemon Junior (787 points) | 38 views

0 votes

2 answers

12

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, 2019 in Databases by anusuccess (5 points) | 157 views

+6 votes

1 answer

13

GATE2019-32
Let the set of functional dependencies $F=\{QR \rightarrow S, \: R \rightarrow P, \: S \rightarrow Q \}$ hold on a relation schema $X=(PQRS)$. $X$ is not in BCNF. Suppose $X$ is decomposed into two schemas $Y$ and $Z$, where $Y=(PR)$ ... $Y$ and $Z$ is dependency preserving and lossless Which of the above statements is/are correct? Both I and II I only II only Neither I nor II

asked Feb 7, 2019 in Databases by Arjun Veteran (431k points) | 2.4k views

+1 vote

2 answers

14

#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, 2019 in Databases by Reshu $ingh (259 points) | 193 views

0 votes

1 answer

15

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, 2019 in Databases by Jyoti Kumari97 (187 points) | 96 views

0 votes

1 answer

16

MadeEasy Workbook: Databases - Database Normalization

asked Jan 23, 2019 in Databases by Jyoti Kumari97 (187 points) | 88 views

0 votes

1 answer

17

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, 2019 in Databases by Hardik Vagadia (345 points) | 89 views

0 votes

0 answers

18

Ace Test Series: DBMS - Functional Dependency

asked Jan 21, 2019 in Databases by Na462 Loyal (7k points) | 69 views

0 votes

0 answers

19

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, 2019 in Databases by Harsh Kumar Active (1.3k points) | 44 views

0 votes

1 answer

20

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, 2019 in Databases by Sukhbir Singh Junior (571 points) | 83 views

0 votes

0 answers

21

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, 2019 in Databases by Naveen Muralidhar (423 points) | 101 views

0 votes

0 answers

22

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, 2019 in Databases by OneZero Active (2.1k points) | 30 views

0 votes

1 answer

23

Ace 2019
Dependency preserving/Lossless ?

asked Jan 9, 2019 in Databases by balchandar reddy san Active (3.3k points) | 93 views

0 votes

0 answers

24

Self-doubt | DBMS | Functional Dependency
Can someone explain the paragraph marked based on relation $r$ given in Figure 7.2? Reference: Database System Concepts by Silberschatz, Korth, Sudarshan 4th Edition.

asked Jan 5, 2019 in Databases by zeeshanmohnavi Active (1k points) | 39 views

+1 vote

1 answer

25

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, 2019 in Databases by Prateek Raghuvanshi Boss (10.8k points) | 185 views

0 votes

1 answer

26

MadeEasy Test Series: Databases - Functional Dependencies
Consider the following relation R(A, B, C, D, E, F, G) and set of functional dependencies. F={BCD → A, BC → E, A → F, F → G, A→G, C → D} Which of the following is minimal cover of F? (A) {BC → A, BC → E, A → F, C → D, A → G} (B) ... → D} (D) {BC → A, BC → E, A → F, C → D} My doubt here is Since (B) covers F, why can't it be a minimal cover?

asked Jan 5, 2019 in Databases by Shivam Kasat Active (3.2k points) | 106 views

+1 vote

1 answer

27

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 (7.5k points) | 102 views

0 votes

0 answers

28

Sel doubt
Relation R (A,B,C,D,E,F) Functional dependency: ABC -->DEF, BC-->EF, EF-->D. Decomposition: R1 (ABCDF), R2 (BCDE). Is this decomposition lossy? Is this decomposition preserve functional dependency? Plz explain how to check functional dependency is preserved or not in decomposition.

asked Dec 24, 2018 in Databases by Raj Kumar 7 Active (1.1k points) | 141 views

+1 vote

1 answer

29

ME test series
Consider relation R(A,B,C,D,E,F,G) with the following functional dependencies AB$\rightarrow$CD , D$\rightarrow$B, AF$\rightarrow$D, DE$\rightarrow$F, C$\rightarrow$G, F$\rightarrow$E, G$\rightarrow$A. What is the highest normal form.

asked Dec 20, 2018 in Databases by Rajat Agrawal007 Junior (675 points) | 93 views

+1 vote

2 answers

30

MadeEasy Test Series: Databases - Functional Dependencies
Consider Relation R(A,B,C,D,E,F,G) and set of Functional dependencies: F = {BCD → A, BC→ E, A→ F, F→ G, C→ D, A→ G} What is the minimal cover of F ? Answer given: BC → A, BC→ E, A→ F, F→ G, C→ D Why the answer cant be: BC → A, BC→ E, A→ F, C→ D, A→ G

asked Dec 20, 2018 in Databases by Shamim Ahmed Active (2.5k points) | 170 views

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