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Recent questions tagged natural-join

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31

Natural Join
What will be the output of Natural Join if there is(are) common attribute(s) in two relations but no common value in these common attribute(s) ? for example Table R A B 6 9 7 1 Table S B C 7 3 5 8 R Natural Join s will be ?

rdfan19 asked in Databases Aug 4, 2017

470 views

3 votes

2 answers

32

Natural Join
What will be the output of Natural join if there is(are) common attribute(s) in two relations but no Common value in these common attribute(s) ? For example Table R A B 9 7 6 9 Table S B C 4 1 8 5 Output of R natural join S will be ?

rdfan19 asked in Databases Aug 4, 2017

3.2k views

2 votes

1 answer

33

[DBMS] Number of tuples in RA

rahul sharma 5 asked in Databases Jul 5, 2017

by rahul sharma 5

1.1k views

4 votes

4 answers

34

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

kauray asked in Databases May 9, 2017

by kauray

3.8k views

0 votes

0 answers

35

ISI-JRF
Consider the relations r1(A, B, C), r2(C, D, E) and r3(E, F). Assume that the set of all attributes constitutes the primary keys of these relations, rather than the individual ones. Let V (C, r1) be 500, V (C, r2) be 1000, V (E, r2) be ... has 1500 tuples, and r3 has 750 tuples, then give the ordering of the natural join of r1, 2 and r3 for its efficient computation. Justify your answer.

kauray asked in Databases Apr 20, 2017

by kauray

586 views

0 votes

1 answer

36

self doubt
If there are no attributes in common between two relations R and S then, what should be the result of (R natural join S)? 1) R x S 2) $\phi$ I think option 2 because of following definition from Korth:

Sushant Gokhale asked in Databases Feb 3, 2017

by Sushant Gokhale

401 views

0 votes

1 answer

37

No of tuples
Ans given: 100

vaishali jhalani asked in Databases Jan 11, 2017

by vaishali jhalani

923 views

2 votes

1 answer

38

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.

rahul sharma 5 asked in Databases Jan 5, 2017

by rahul sharma 5

986 views

3 votes

2 answers

39

Test by Bikram | Databases | Test 1 | Question: 22
Consider the following set of relations: EMP(eno, ename, dno) DEPT(dno,dname) Primary key columns are in bold and dno in EMP is a foreign key referring primary key of DEPT table. Now consider the following queries: QUERY : 1 SELECT * FROM emp e ... Query:1 and Query:2 returns different no of columns. I, II only I, IV only II, III only III, IV only

Bikram asked in Databases Nov 26, 2016

by Bikram

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40

Sayan Das 1 asked in Databases Nov 23, 2016

223 views

8 votes

3 answers

41

Number of tuples in natural join
Consider the following relations: $R_1(A,B,C)$ and $R_2(A,D,E)$. $R_1$ has 1000 records and $R_2$ has 2000 records. The attribute $A$ in $R_2$ is referencing attribute $A$ in $R_1$. Let $X$ be minimum number of records in $R_1$ ⨝ $R_2$ and $Y$ be the maximum number of records in $R_1$⨝$R_2$. The sum of $(X+Y)$ is _______.

GateAspirant999 asked in Databases Oct 31, 2016

by GateAspirant999

11.2k views

1 vote

1 answer

42

Nested loop join vs blocked nested loop join
If - relation r has br blocks and nr records, - relation s has bs blocks and ns records, - memory can hold exactly one block of r and one block of s at any point in time, then what is the formula for number block accesses required ... (a) nested loop join (b) blocked nested loop join Also which book discusses this topic? And is it in syllabus for gate?

GateAspirant999 asked in Databases Oct 30, 2016

by GateAspirant999

2.0k views

1 vote

2 answers

43

Natural join
Q1. Suppose in an SQL query I have natural join as : from R1 natural join R2 natural join R3 natural join R4 then how does the natural join works? According to me, First R1 joins with R2 matching common attributes value between R1 and R2 then the ... such as name and course_id, without the relation names " but teaches.course_id is used in the query. WHY? It's not allowed.

Shivam Chauhan asked in Databases Oct 20, 2016

by Shivam Chauhan

926 views

5 votes

2 answers

44

KISHALAY DAS asked in Databases Oct 19, 2016

by KISHALAY DAS

1.5k views

2 votes

2 answers

45

UGC NET CSE | August 2016 | Part 3 | Question: 9
Suppose database table $T1(P, R)$ currently has tuples ${(10, 5), (15, 8), (25, 6)}$ and table $T2 (A, C)$ currently has ${(10, 6), (25, 3), (10, 5)}$. Consider the following three relational algebra queries $RA1, RA2$ and $RA3$: ... RA2 and RA3 are given by : $2, 4, 2$ respectively $2, 3, 2$ respectively $3, 3, 1$ respectively $3, 4, 1$ respectively

makhdoom ghaya asked in Others Sep 30, 2016

by makhdoom ghaya

2.9k views

0 votes

1 answer

46

join
Comment on the following two statements Natural Join produce cartecian product of two tables on joing two relations with no matching coloums Full Outer Join produce cartecian product of two tables on joing two relations with no matching coloums

pC asked in Databases Sep 9, 2016

by pC

505 views

8 votes

1 answer

47

Question on Join
Let us consider 3 relations R1(ABD), R2(BCE) and R3(CF). The primary keys of R1 , R2 and R3 are A, B and C respectively. The number of tuples in R1, R2 and R3 are 50,40,80 respectively. Maximum size of R1*R2*R3 where * denotes natural join.

Aakash Das asked in Databases Jun 25, 2016

1.9k views

3 votes

2 answers

48

maximum no of tuples
Consider the relation R1( P, Q, R, S ) and R2 ( R, G, T, U ) The relation R1 has 20 tuples and R2 has 10 tuples then maximum number of tuples in R1 ⟕ R2 is .......................?

saket nandan asked in Databases Mar 21, 2016

by saket nandan

2.3k views

1 vote

2 answers

49

dbms
Consider the relation $R(X Y Z)$ has the following tuples X Y Z 1 2 3 1 2 4 3 2 1 _________ tuples in the result of following relational algebra expression $(\underset{X,Y}\pi R ) \underset{R,Y < S,Y}\bowtie (\underset{S(X,Y)}\rho (\underset{Y,Z}\pi R))$

Registered user 7 asked in Databases Feb 5, 2016

by Registered user 7

2.6k views

1 vote

3 answers

50

Relation between Intersection and natural inner join on common column
When , then the cost of computing is (A) the same as R S (B) greater the R S (C) less than R S (D) cannot say anything

Purple asked in Databases Jan 24, 2016

by Purple

1.7k views

1 vote

2 answers

51

Left outer join
Given answer for this question is: Should last row be present in the result. Please check

shikharV asked in Databases Jan 13, 2016

556 views

1 vote

1 answer

52

Maximum and minimum size of the join of two relations
I am confused about this problem: Relation A -> m tuples Relation B -> n tuples What is the maximum and minimum size of natural join? According to this, maximum can be -> min(m,n) and minimum can be 0. I want to know if it is asked that what is maximum and minimum size on join operation (not natural join) will the answer get changed?

shikharV asked in Databases Dec 8, 2015

8.5k views

6 votes

5 answers

53

GATE2004_13 Let R1 (A, B, C) and R2 (D, E) be two relation schema, where the primary key...
----SPOILERS------ My doubt is that why option "c" shouldnt be an answer, as join is performed on the C not equal to D, and there will be no case where C is not equal to d as it satisfies referential integrity constraints. . ?

learncp asked in Databases Sep 5, 2015

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0 votes

3 answers

54

if natural join is done then min and max no. of tuples if referential integrity is taken and not
R(ABC) S(BDE) F:A->B B ->C B->D D->E AND R HAS 100 TUPLES AND S HAS 200

uzumzki asked in Databases Aug 17, 2015

2.0k views

31 votes

2 answers

55

GATE CSE 2015 Set 2 | Question: 32
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 $R_2$. Consider the following tuples of the form $(A,B,C):$ ... contains all $a, b, c, d, e, f, g$. $R$ contains $e, f, g$ but not $a, b$. $R$ contains $e$ but not $f, g$.

go_editor asked in Databases Feb 12, 2015

9.0k views

42 votes

4 answers

56

GATE IT 2006 | Question: 14
Consider the relations $r_{1}\text{(P, Q, R)}$ and $r_{2}\text{(R, S, T)}$ with primary keys $\text{P}$ and $\text{R}$ respectively. The relation $r_{1}$ contains $2000$ tuples and $r_{2}$ contains $2500$ tuples. The maximum size of the join $r_1⋈ r_2$ is : $2000$ $2500$ $4500$ $5000$

Ishrat Jahan asked in Databases Oct 31, 2014

by Ishrat Jahan

17.2k views

41 votes

8 answers

57

GATE CSE 2010 | Question: 43
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 $R \bowtie S$? $100$ $200$ $300$ $2000$

go_editor asked in Databases Sep 30, 2014

13.1k views

45 votes

5 answers

58

GATE CSE 2005 | Question: 30
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? $s \subset r$ $r \cup s =r$ $r \subset s$ $r*s=s$

Kathleen asked in Databases Sep 22, 2014

16.2k views

64 votes

7 answers

59

GATE CSE 2004 | Question: 14
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? $8, 8$ $120, 8$ $960, 8$ $960, 120$

Kathleen asked in Databases Sep 18, 2014

28.5k views

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