Recent questions tagged database-normalization

–1 vote

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1

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

asked 4 days ago in Databases by Harsh Kumar Junior (887 points) | 23 views

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2

GA_Testseries
is this in 3NF?

asked 5 days ago in Databases by aditi19 Active (2.1k points) | 51 views

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3

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 5 days ago in Databases by aditi19 Active (2.1k points) | 34 views

+1 vote

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4

GA_Testseries

asked 5 days ago in Databases by aditi19 Active (2.1k points) | 25 views

+1 vote

1 answer

5

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

asked 6 days ago in Databases by gatecrack (131 points) | 44 views

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6

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

asked 6 days ago in Databases by Shivam Kasat Junior (817 points) | 17 views

+1 vote

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7

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 in Databases by aditi19 Active (2.1k points) | 98 views

+1 vote

1 answer

8

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 in Databases by Ayush Upadhyaya Boss (18.9k points) | 69 views

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1 answer

9

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 in Databases by Lakshman Patel RJIT Boss (20.4k points) | 175 views

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10

Self-doubt [Foreign keys and Third Normal Form]

asked Nov 19 in Databases by Harsh Kumar Junior (887 points) | 41 views

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1 answer

11

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 in Databases by Kshitij Hansda (119 points) | 70 views

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12

#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 in Databases by Rameesh (363 points) | 96 views

+1 vote

1 answer

13

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

asked Oct 28 in Databases by aditi19 Active (2.1k points) | 60 views

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14

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 in Databases by Prince Sindhiya Loyal (5.3k points) | 26 views

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15

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 in Databases by jatin khachane 1 Active (3.3k points) | 24 views

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2 answers

16

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 in Databases by jatin khachane 1 Active (3.3k points) | 33 views

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17

Self Doubt
While checking for normal forms Why we only check conditions only on F not on F+ eg R(A,B,C) F = {A->B , B->C} is in 3NF or not ? We will apply defination of 3NF i,e either LHS should be super key or RHS should be prime attribute ON ... if decomposed relation is in particular normal form we apply check on ALL IMPLIED FDs from F ?? In below ex should all implied FDs be checked ??

asked Oct 23 in Databases by jatin khachane 1 Active (3.3k points) | 25 views

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18

Second Normal Form

asked Oct 21 in Databases by Na462 Loyal (7.5k points) | 112 views

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1 answer

19

Self-Doubt
We say every bcnf is 3nf also but suppose in a bcnf relation the dependency is not preserved then how can we say that it is in 3nf since every 3nf must be dependency preserving.

asked Oct 16 in Databases by satendra (315 points) | 27 views

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1 answer

20

Normalisation
Difference between composite and compound key??

asked Oct 5 in Databases by Raghav Khajuria Junior (585 points) | 42 views

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21

Normalzation

asked Oct 4 in Databases by Vaishnavi01 (215 points) | 50 views

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2 answers

22

Normal Form (doubt)
Here directly dependency not given. Which normal form it doesnot hold , how to eliminate it? I got here 1:m, or 1:1 dependency. Is it any value to ans this question?

asked Oct 2 in Databases by srestha Veteran (104k points) | 59 views

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2 answers

23

doubt in databases

asked Sep 26 in Databases by goluabhinan (101 points) | 125 views

+1 vote

3 answers

24

doubt in databases

asked Sep 26 in Databases by goluabhinan (101 points) | 143 views

0 votes

1 answer

25

Why 3NF is inadequate in below situations ?

asked Sep 25 in Databases by radha gogia Loyal (7.9k points) | 83 views

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1 answer

26

Normal forms,DBMS
Consider relation R with set functional dependencies (F) as: $R(ABCD)$ and $F \left \{ AB \rightarrow CD, C \rightarrow A, A \rightarrow C \right \}$. 1) If the above relation is decomposed into R1 (CBD), R2 (CA) then ... also dependency preserving (B) Lossy but dependency preserving (C) Lossy and also dependencies are not preserved (D) Lossless but dependencies are not preserved

asked Sep 23 in Databases by Bhavna (51 points) | 52 views

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27

Normalization - transitive dependency
In the books, it is written that a transitive dependency is one in which a non-key attribute is determining another non-key attribute. So, if ${R (A,B,C,D,E,F)}$ be a relation and ${ABC}$ ... about those dependencies in which the LHS is a combination of key and non-key attributes ? for example, what about ${ABD \to E}$ ?

asked Sep 15 in Databases by Harsh Kumar Junior (887 points) | 33 views

+1 vote

1 answer

28

Test Series

asked Aug 29 in Databases by ben10 (373 points) | 101 views

0 votes

1 answer

29

Self doubt
Join of two 3NF relations may be yeilds a 3NF relation True/False? If true explain with example? If false explain why?

asked Aug 7 in Databases by eswaraleti143 (21 points) | 47 views

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