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Recent questions tagged relational-algebra

3 votes
2 answers
213
Test by Bikram | Databases | Test 2 | Question: 16
$\sigma_{A=B \text{ and } B=C \text{ and } C=A} \bigg( \Pi_A (R) \times \Pi_B (R) \times \Pi_C (R) \bigg)$ The number of rows returned by the above relational algebraic expression is ________.
$\sigma_{A=B \text{ and } B=C \text{ and } C=A} \bigg( \Pi_A (R) \times \Pi_B (R) \times \Pi_C (R) \bigg)$The number of rows returned by the above relational algebraic ex...
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2 votes
1 answer
214
Relational algebra gateforum sample questions
https://gateoverflow.in/?qa=blob&qa_blobid=7899832711610886100 How can we know that when we have to use natural join and when Cartesian product??
https://gateoverflow.in/?qa=blob&qa_blobid=7899832711610886100How can we know that when we have to use natural join and when Cartesian product??
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3 votes
1 answer
215
Relational Algebra
Consider the following schema: Student (Sid, Sname, age) Course Info (Cid, Cname, Instructor SSN) Enroll (Sid, Cid, grade). The relational algebra expression for “find the Cid’s of courses enrolled by two different students” is ??
Consider the following schema:Student (Sid, Sname, age)Course Info (Cid, Cname, Instructor SSN)Enroll (Sid, Cid, grade).The relational algebra expression for “find the ...
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1 votes
3 answers
216
DBMS Relational Algebra
How the following two expressions are equal? The LHS will remove duplicates but RHS will not.Please explain
How the following two expressions are equal?The LHS will remove duplicates but RHS will not.Please explain
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1 votes
0 answers
217
Dbms relation algebra
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4 votes
1 answer
218
Relation and Partial order
Is (S, R) a poset if S is the set of all people in the world and (a, b) ∈ R, where a and b are people, if a is not taller than b?
Is (S, R) a poset if S is the set of all people in the world and (a, b) ∈ R, where a and b are people,if a is not taller than b?
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4 votes
2 answers
220
DBMS Conditional Join
Does out put of conditional join contains duplicates?I know that it gives distinct in natural join as the projection operator removes duplicate rows. But in conditional join does this thing holds true?
Does out put of conditional join contains duplicates?I know that it gives distinct in natural join as the projection operator removes duplicate rows. But in conditional j...
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4 votes
4 answers
222
Join Number of Tuples
Suppose you are given relations r(A, B) and s(A, C). Suppose that r has 10000 tuples, and s has 5000 tuples. Suppose attribute r.A has 1001 distinct values, and s.A also has 1001 distinct values. The maximum possible size of the join result is
Suppose you are given relations r(A, B) and s(A, C). Suppose that r has 10000 tuples, and s has 5000 tuples. Suppose attribute r.A has 1001 distinct values, and s.A also ...
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52 votes
5 answers
223
GATE CSE 2017 Set 1 | Question: 46
Consider a database that has the relation schema CR(StudentName, CourseName). An instance of the schema CR is as given below. ... $T2 \leftarrow CR\div T1$ The number of rows in $T2$ is ______________ .
Consider a database that has the relation schema CR(StudentName, CourseName). An instance of the schema CR is as given below.$$\begin{array}{|c|c|} \hline \textbf{Student...
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3 votes
3 answers
226
Doubt about joins on keys
Consider the following relation: R (A B C) A primary key with 100 tuples. S (E F G) E primary key with 50 tuples. T (AE D) AE primary key with 80 tuples. U (D G H) H primary key with 10 tuples. The maximum number of possible records in the result of _______.
Consider the following relation:R (A B C) A primary key with 100 tuples.S (E F G) E primary key with 50 tuples.T (AE D) AE primary key with 80 tuples.U (D G H) H primary ...
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1 votes
1 answer
228
Mock Test
Is statement 1 true for all safe expressions ?
Is statement 1 true for all safe expressions ?
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0 votes
1 answer
229
made-easy mock test2
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1 votes
0 answers
230
Testbook
What if depositor and borrower contain duplicate names? They havent given name as primary key?
What if depositor and borrower contain duplicate names? They havent given name as primary key?
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9 votes
1 answer
233
Relational operators property
An operator on relations is called monotone whenever we add a tuple to one of its arguments, the result contains all the tuples that it contained before adding the tuple plus perhaps more tuples. Which of the following operator is monotone? $\Join$ $\cap$ $-$ $\large \sigma$
An operator on relations is called monotone whenever we add a tuple to one of its arguments, the result contains all the tuples that it contained before adding the tuple ...
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2 votes
1 answer
236
Natural vs conditional join dbms
Say I have two tables and they have some attributes in common, assume x is common, now will x will appear once in the output or twice for following cases? Natural join Cross product Conditional join Please explain.
Say I have two tables and they have some attributes in common, assume x is common, now will x will appear once in the output or twice for following cases? Natural joinCro...
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