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Recent questions tagged superkeys

1 vote
1 answer
1
Consider the relation $R\left ( A,B,C,D,E \right )$ $A\rightarrow BC$ $C\rightarrow E$ $B\rightarrow D$ $E\rightarrow A$ Total number of superkeys present in relation will be ____________________
asked May 9, 2019 in Databases srestha 497 views
1 vote
2 answers
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Consider the following relation R(A1, A2,...A15) with (A1,A2, ... A6) of relation R are simple candidate key. The number of possible superkey in relation R is_
asked Jan 30, 2019 in Databases Ram Swaroop 430 views
0 votes
1 answer
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Consider the following relation: R (A1, A2, ….An) and every (n-2) attributes of R forms a candidate key. How many super keys are there in R?
asked Jan 22, 2019 in Databases kumar.dilip 479 views
0 votes
3 answers
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Maximum number of superkeys for the relation schema $R(X,Y,Z,W)$ with $X$ as the key is $6$ $8$ $9$ $12$
asked Dec 7, 2018 in Databases Arjun 524 views
3 votes
1 answer
5
Consider the relation R(A,B,C,D,E) with the functional dependencies : A → B, B → C, C → A, D → E, and E → D The Maximum possible super-keys of R is ______________?
asked Dec 7, 2018 in Databases naveen bhatt 339 views
0 votes
1 answer
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How many Super keys Possible for R(A,B,C,D,E) with 1. {A,BC,DE} as the keys ? 2. {A,BC,CDE} as the keys ?
asked Oct 13, 2018 in Databases Na462 226 views
0 votes
1 answer
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Relation R(A1, A2, A3 ..... An) n attributes. On this relation m simple candidate key (m ≤ n). How many super keys possible in this relation? A. 2m – 1 B. (2n – 1) ⋅ 2n-m C. 2n – 1 D. (2m – 1) 2n-m One way is by taking instances and solve it, but plz without it what's the logic behind the answer?
asked May 17, 2018 in Databases Na462 795 views
0 votes
3 answers
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Consider the following relational schema R(ABCDE). The number of super keys in relation R if every two attributes of relation R is candidate keys are __________. Please explain a general method to solve
asked May 12, 2018 in Databases Na462 359 views
0 votes
0 answers
9
How to calculate super key of any relation? Pls explain with example.
asked Apr 8, 2018 in Databases Dhoomketu 159 views
1 vote
1 answer
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R (A1, A2, ….An) and every (n-2) attributes of R forms a candidate key. How many super keys are there in R? a) $_{n-2}^{n}\textrm{C}$ b) $_{n-2}^{n}\textrm{C}$ * 4 c) $_{n-2}^{n}\textrm{C}$ * n d) $_{n-2}^{n}\textrm{C}$ + n +1
asked Jan 18, 2018 in Databases hacker16 812 views
2 votes
0 answers
11
a relation R(A,B,C,D,E,F,G,H) and set of functional dependencies are {CH->G,A->BC,B->CFH,E->A,F->EG } then how many possible super keys are present ? https://gateoverflow.in/42238/to-calculate-how-many-no-of-super-keys Is my approach right? Since candidate keys are (AD) ... ,ADF,BDE,BDF, EDF,AED,ADEF,ABDE,AFBE,AFBD,ABDEF}= 15 ways total = 15* 8 = 120 ways ....Can someone plz confirm it.... thank u
asked Jan 12, 2018 in Databases Pawan Kumar 2 377 views
2 votes
3 answers
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Let the relation R(X, Y, Z, A, B) with given functional dependencies X -> YZ Z -> A A -> B AZ -> X The number of super keys possible__________ ? Please answer with an explanation.
asked Aug 29, 2017 in Databases Warlock lord 293 views
5 votes
2 answers
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Consider a relation $R$ with $2n$ attributes. Assume any $2n/2$ of the attributes constitutes key. Total number of super keys possible are: $^{2n}C_{2^{n-1}}\times \left(2\right)^{2^{n-1}}$ $^{2n}C_{2^{n-1}} + \left(2\right)^{2^{n-1}}$ $^{2n}C_{2^{n-1}} - \left(2\right)^{2^{n-1}}$ $^{2n}C_{2^{n-1}} \div \left(2\right)^{2^{n-1}}$
asked Jan 18, 2016 in Databases Tushar Shinde 562 views
3 votes
1 answer
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