Recent questions tagged natural-join - GATE CSE Doubts

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ME Test Series
I have a doubt, How many rows will be returned when All values of R2.A will be Null….in this case number of rows Natural Join should give 0 rows ….what will be minimum number of rows???

asked 4 days ago in Databases by vipin.gautam1906 (5 points) | 16 views

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Joins in Relational Algebra (Self Doubt) while reading Elmasri Navathe

asked 5 days ago in Databases by shubhojit1412 (5 points) | 15 views

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GATE2004-14 Video Solution
Consider the following relation schema pertaining to a students database: Students (rollno, name, address) Enroll (rollno, courseno, coursename) where the primary keys are shown underlined. The number of tuples in the student and Enroll tables are $120$ and $8$ respectively. What ... (Student * Enroll), where *' denotes natural join? $8, 8$ $120, 8$ $960, 8$ $960, 120$

asked Apr 18, 2020 in Databases by admin (569 points) | 20 views

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GATE2005-30 Video Solution
Let r be a relation instance with schema R = (A, B, C, D). We define $r_1 = \pi_{A, B, C} (R)$ and $r_2=\pi_{A, D} (r)$. Let $s =r_1 \: * \: r_2$ where $*$ denotes natural join. Given that the decomposition of $r$ into $r_1$ and $r_2$ is lossy, which one of the following is TRUE? $s \subset r$ $r \cup s =r$ $r \subset s$ $r*s=s$

asked Apr 18, 2020 in Databases by admin (569 points) | 9 views

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GATE2010-43 Video Solution
The following functional dependencies hold for relations $R(A, B, C)$ and $S(B, D, E).$ $ B \to A$ $A \to C$ The relation $R$ contains $200$ tuples and the relation $S$ contains $100$ tuples. What is the maximum number of tuples possible in the natural join $R \bowtie S$? $100$ $200$ $300$ $2000$

asked Apr 18, 2020 in Databases by admin (569 points) | 4 views

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GATE2006-IT-14 Video Solution
Consider the relations r1(P, Q, R) and r2(R, S, T) with primary keys P and R respectively. The relation r1 contains 2000 tuples and r2 contains 2500 tuples. The maximum size of the join r1⋈ r2 is : 2000 2500 4500 5000

asked Apr 18, 2020 in Databases by admin (569 points) | 7 views

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GATE2015-2-32 Video Solution
Consider two relations $R_1(A,B)$ with the tuples $(1,5), (3,7)$ and $R_2(A,C) = (1,7),(4,9)$. Assume that $R(A,B,C)$ is the full natural outer join of $R_1$ and $R_2$ ... $a, b, c, d, e, f, g$. $R$ contains $e, f, g$ but not $a, b$. $R$ contains $e$ but not $f, g$.

asked Apr 18, 2020 in Databases by admin (569 points) | 9 views

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