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Recent questions tagged relational-algebra

2 votes
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272
relational algebra
THE DIFFERENCE BETWEEN FOLLOWING 2 EXPRESSIONS? a. (selection)year≥2009(takes) NATURAL JOIN  student b. (selection)year≥2009(takes NATURAL JOIN student)
THE DIFFERENCE BETWEEN FOLLOWING 2 EXPRESSIONS?a. (selection)year≥2009(takes) NATURAL JOIN  studentb. (selection)year≥2009(takes NATURAL JOIN student)
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27 votes
3 answers
274
TIFR CSE 2013 | Part B | Question: 19
In a relational database there are three relations: $Customers = C\textsf{(CName)}$, $Shops = S \textsf{(SName)}$, $Buys = B\textsf{(CName, SName)}$ ... $S - \Pi _{\textsf{SName}}((C \times S) - B)$ None of the above
In a relational database there are three relations:$Customers = C\textsf{(CName)}$,$Shops = S \textsf{(SName)}$,$Buys = B\textsf{(CName, SName)}$.Which of the following r...
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1 votes
2 answers
275
Total number of tuples
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5 votes
4 answers
278
Why is the maximum number of tuples in full outer join equal to m*n ?
Why is the maximum number of tuples in full outer join equal to m*n, where m is the number of attributes in one relation and n is the attribute count in other ? Can someone give an example to illustrate this ?
Why is the maximum number of tuples in full outer join equal to m*n, where m is the number of attributes in one relation and n is the attribute count in other ?Can someon...
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2 votes
4 answers
280
True or False: Relational algebra cannot perform aggregate function
True or False: Relational algebra cannot perform aggregate function
True or False: Relational algebra cannot perform aggregate function
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24 votes
3 answers
285
GATE CSE 1995 | Question: 27
Consider the relation scheme. ... for the publisher with PNAME='TECHNICAL PUBLISHERS'. Get the names of all authors who have published a book for any publisher located in Madras
Consider the relation scheme.$$\begin{array}{ll} \text{AUTHOR} & \text{(ANAME, INSTITUTION, ACITY, AGE)} \\\hline \text{PUBLISHER} & \text{(PNAME, PCITY)} \\\hline \te...
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26 votes
5 answers
287
GATE CSE 1994 | Question: 3.8
Give a relational algebra expression using only the minimum number of operators from $(∪, −)$ which is equivalent to $R$ $∩$ $S.$
Give a relational algebra expression using only the minimum number of operators from $(∪, −)$ which is equivalent to $R$ $∩$ $S.$
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23 votes
1 answer
293
GATE CSE 1998 | Question: 1.33
Given two union compatible relations $R_1(A, B)$ and $R_2 (C, D)$, what is the result of the operation $R_1 \Join_{ A = C \wedge B = D} R_2$? $R_1 \cup R_2$ $R_1 \times R_2$ $R_1 – R_2$ $R_1 \cap R_2$
Given two union compatible relations $R_1(A, B)$ and $R_2 (C, D)$, what is the result of the operation $R_1 \Join_{ A = C \wedge B = D} R_2$?$R_1 \cup R_2$$R_1 \times R_2...
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38 votes
1 answer
294
GATE CSE 1999 | Question: 1.18, ISRO2016-53
Consider the join of a relation $R$ with a relation $S$. If $R$ has $m$ tuples and $S$ has $n$ tuples then the maximum and minimum sizes of the join respectively are $m+n$ and $0$ $mn$ and $0$ $m+n$ and $|m-n|$ $mn$ and $m+n$
Consider the join of a relation $R$ with a relation $S$. If $R$ has $m$ tuples and $S$ has $n$ tuples then the maximum and minimum sizes of the join respectively are$m+n$...
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42 votes
4 answers
297
GATE CSE 2003 | Question: 30
Consider the following SQL query Select distinct $a_1, a_2, , a_n$ from $r_1, r_2, , r_m$ ... $\Pi_{a_1, a_2, a_n} \sigma_p \left(r_1 \cap r_2 \cap \dots \cap r_m \right)$
Consider the following SQL querySelect distinct $a_1, a_2, …, a_n$from $r_1, r_2, …, r_m$where PFor an arbitrary predicate P, this query is equivalent to which of the...
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52 votes
3 answers
299
GATE CSE 2001 | Question: 1.25
Let r and s be two relations over the relation schemes R and S respectively, and let A be an attribute in R. The relational algebra expression $\sigma_{A=a}(r \bowtie s)$ is always equal to $\sigma_{A=a}(r)$ $r$ $\sigma_{A=a}(r) \bowtie s$ None of the above
Let r and s be two relations over the relation schemes R and S respectively, and let A be an attribute in R. The relational algebra expression $\sigma_{A=a}(r \bowtie s)...
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