Recent questions tagged database-normalization

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1

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 (7 points) | 43 views

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2 answers

2

#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 (345 points) | 54 views

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3

Made easy practice book
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 (225 points) | 16 views

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4

Made easy theory book

asked Jan 23 in Databases by Jyoti Kumari97 (225 points) | 33 views

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1 answer

5

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 (497 points) | 36 views

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6

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 (1k points) | 16 views

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7

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 (309 points) | 21 views

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8

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 (1.3k points) | 11 views

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9

Ace 2019
Dependency preserving/Lossless ?

asked Jan 9 in Databases by balchandar reddy san Active (2.7k points) | 57 views

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10

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) | 48 views

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11

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) | 27 views

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12

Made easy test series database systems
Can anybody please explain the concept behind this answer, and why my answer is considered wrong ?

asked Dec 28, 2018 in Databases by Harsh Kumar Active (1k points) | 56 views

+1 vote

2 answers

13

Made Easy Test
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 (2.3k points) | 104 views

–1 vote

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14

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 (1k points) | 52 views

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15

GA_Testseries
is this in 3NF?

asked Dec 10, 2018 in Databases by aditi19 Active (2.3k points) | 88 views

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16

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 (2.3k points) | 49 views

+1 vote

0 answers

17

GA_Testseries

asked Dec 10, 2018 in Databases by aditi19 Active (2.3k points) | 33 views

+1 vote

1 answer

18

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 (137 points) | 70 views

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19

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 (1.9k points) | 24 views

+2 votes

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20

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 (2.3k points) | 119 views

+1 vote

1 answer

21

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 (24.5k points) | 95 views

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1 answer

22

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 (29k points) | 208 views

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23

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 (1k points) | 51 views

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1 answer

24

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 (133 points) | 87 views

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25

#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 (451 points) | 107 views

+1 vote

1 answer

26

#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 (2.3k points) | 62 views

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27

doubt test dbms
S1:1:1, 1:N and N:M relationships are also known as HAS-A relationships. S2:An entity is something that can be identified in the user's work environment; something that the users want to track S1 is true and S2 is false S1 and S2 both are false S1 is false and S2 is true S1 and S2 both are true

asked Oct 25, 2018 in Databases by Prince Sindhiya Loyal (6.2k points) | 31 views

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0 answers

28

Self doubt
Notice that we can always map 1:1 or l:N relationships in a manner similar M:N to relationships by using the cross-reference (relationship relation) approach, as we discussed earlier. This alternative is particularly useful when few relationship instances exist, in ... the entities or only those who are participating in relationship TO AVOID NULLS ex: Table 1 or table how will it be ?

asked Oct 24, 2018 in Databases by jatin khachane 1 Loyal (6.4k points) | 27 views

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2 answers

29

Self Doubt
A relation R is in 2NF if every non-prime attribute of R is fully functionally dependent on every key of R true or false R(A,B,C) F {A->B,B->C} Here key = A R is in 2NF So is C is fully functional dependent on every key here ?. It is not dependent on key infact ?

asked Oct 24, 2018 in Databases by jatin khachane 1 Loyal (6.4k points) | 38 views

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