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Recent questions tagged relational-calculus
2
votes
0
answers
31
Relational algebra
I have two doubts: 1) A natural join B What will be the result when B don't have any tuple in it. Like in B their is relational algebra expression which is selecting Cars of green color but their is no green color car in table. What will be the ... B In above divison if B is a relational algebra expression returning nothing ( like the B in case 1). What will be the result ?
♥_Less
asked
in
Programming
Jan 14, 2018
by
♥_Less
318
views
relational-algebra
databases
relational-calculus
joins
1
vote
2
answers
32
Test Series
Let r and s be two relations over the relational schemas R and S respectively, and let A be an attribute in R. Then the relation algebra expression σ(A=a) (r⋈s) is always equal to( Marks: -0.33 ) σ(A=a) (r)⋈s r None of the above σ(A=a) (r)
ankit_thawal
asked
in
Databases
Jan 2, 2018
by
ankit_thawal
351
views
databases
relational-calculus
0
votes
0
answers
33
Tuple relational calculus
What does the following tuple relational calculus query produce? • Student (Student_name, street, city) • Score (Student_name, Branch_name, marks) • Branch (Branch_name, HOD) • Manages (Student_name, Faculty_name)
Tuhin Dutta
asked
in
Databases
Dec 10, 2017
by
Tuhin Dutta
484
views
relational-calculus
databases
tuple-relational-calculus
0
votes
0
answers
34
Tuple relational calculus
Student (Student_name, street, city) • Score (Student_name, Branch_name, marks) • Branch (Branch_name, HOD) • Manages (Student_name, Faculty_name) What does the following tuple relational calculus query produce?
Tuhin Dutta
asked
in
Databases
Dec 10, 2017
by
Tuhin Dutta
291
views
databases
relational-calculus
tuple-relational-calculus
0
votes
0
answers
35
relational calculus
Parshu gate
asked
in
Databases
Dec 5, 2017
by
Parshu gate
709
views
relational-calculus
databases
tuple-relational-calculus
relational-algebra
2
votes
1
answer
36
Relational algebra
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 equal to r2⋈ r1 true or false?
learner_geek
asked
in
Databases
Dec 3, 2017
by
learner_geek
1.2k
views
relational-calculus
joins
relations
relational-algebra
databases
2
votes
3
answers
37
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” (no options)
shaurya vardhan
asked
in
Databases
Dec 3, 2017
by
shaurya vardhan
5.2k
views
databases
relational-algebra
relations
relational-calculus
1
vote
0
answers
38
#dbms query
how to read/breakdown/understand this query? which part wil be solved first? {t∣t∈πR−S(r)∧∀u∈s(∃v∈r(u=v[S]∧t=v[R−S]))}
iarnav
asked
in
Databases
Dec 2, 2017
by
iarnav
161
views
databases
relational-calculus
tuple-relational-calculus
0
votes
1
answer
39
Sql query
Please explain below query step by step and what does it mean?
learner_geek
asked
in
Databases
Nov 29, 2017
by
learner_geek
366
views
sql
databases
self-doubt
relational-calculus
1
vote
0
answers
40
#DBMS Explain these Relational Calculus Queries from GATE Question!
{t∣∃u∈R1(t[A]=u[A])∧¬∃s∈R2(t[A]=s[A])} {t∣∀u∈R1(u[A]="x"⇒∃s∈R2(t[A]=s[A]∧s[A]=u[A]))} Someone please explain how to read this queries or what does each query means in simple English. I ... only one tuple variable ranges over whole relation then what is this u? These are from - https://gateoverflow.in/742/gate2001-2-24
iarnav
asked
in
Databases
Nov 29, 2017
by
iarnav
786
views
relational-calculus
databases
tuple-relational-calculus
0
votes
1
answer
41
TUPLE CALCULUS
Parshu gate
asked
in
Databases
Nov 6, 2017
by
Parshu gate
937
views
relational-calculus
databases
tuple-relational-calculus
2
votes
0
answers
42
self doubt
in the question below in relational algebra if we use projection the relation is considered as a set and hence duplicates are not allowed will even trc and drc follow the same rule ?? rest all i understood only this point is doubtful https://gateoverflow.in/1546/gate2013_35 please clarify
Venkat Sai
asked
in
Databases
Oct 3, 2017
by
Venkat Sai
434
views
databases
tuple-relational-calculus
domain
relational-calculus
2
votes
1
answer
43
Test by Bikram | Databases | Test 2 | Question: 29
Let Depositor and Lender be relational schemas such that Depositor = {a/c number, cname , balance, branch} & Lender ={loan_number ,cname, amount , branch}. Now, consider the following queries on the database: Query $1$ ... 3 give same result. Query 1 and Query 3 give same result. Query 1, Query 2 and Query 3 give different results.
Bikram
asked
in
Databases
Aug 26, 2017
by
Bikram
334
views
tbb-dbms-2
databases
relational-calculus
3
votes
1
answer
44
SQL and Tuple Calculus
Q. Given the relational schema : ENROLL (S#, C#, Section), S# is student number. TEACH (Prof, C#, Section), C# is course number. ADVISE (Prof, S#), Prof is Thesis advisor of S# PRE-REQ (C#, pre-C#), pre-c# is prerequisite course. GRADE ( ... of the same course. (iv) List all students number and course number (v) List the student number and course number who got grade A
Tushar Pandey
asked
in
Databases
Aug 26, 2017
by
Tushar Pandey
1.7k
views
relational-calculus
databases
tuple-relational-calculus
1
vote
0
answers
45
stackoverflow
I have to solve the queries using tuple relational calculus and I just want to know if I did them correctly. I'm using this database: EMPLOYEE: fname , minit , lname, ssn , bdate , address , sex , salary , superssn , dno DEPARTMENT: dname dnumber , ... a.Salary > b.Salary))} Any help will be much appreciated. edit: Assume that only one employee can have the highest/lowest salary.
shashank023
asked
in
Databases
Jul 16, 2017
by
shashank023
401
views
tuple-relational-calculus
relational-calculus
48
votes
5
answers
46
GATE CSE 2017 Set 1 | Question: 41
Consider a database that has the relation schemas EMP(EmpId, EmpName, DeptId), and DEPT(DeptName, DeptId). Note that the DeptId can be permitted to be NULL in the relation EMP. Consider the following queries on the database expressed in tuple relational calculus. { ... Which of the above queries are safe? I and II only I and III only II and III only I, II and III
Arjun
asked
in
Databases
Feb 14, 2017
by
Arjun
20.4k
views
gatecse-2017-set1
databases
relational-calculus
safe-query
normal
1
vote
1
answer
47
Mock Test
Is statement 1 true for all safe expressions ?
Harsh181996
asked
in
Databases
Jan 24, 2017
by
Harsh181996
583
views
databases
relational-algebra
relational-calculus
1
vote
1
answer
48
Tuple relational calculus
An undirected simple graph is represented as G(a,b) and a tuple (x,y)€ G if x and y are adjacent vertices. which of the following can not be computed by a TRC query ? (A) Set of vertices who belongs to four length cycle (B) Set of vertices ... zero (C) Set of vertices which belongs to some cycle (D) Set of vertices which have degree n-1 where (n=total number of vertices)
Geet
asked
in
Databases
Jan 14, 2017
by
Geet
425
views
databases
tuple-relational-calculus
relational-calculus
0
votes
0
answers
49
Given the following relational schemas
Given the following relational schemas Student (studId, name, age, sex, deptNo, advisor) Department (deptId, DName, hod, phoneNo) Which of the following will be the TRC query to obtain the department names that do not have any girl students? {d.Dname | department(d) ∧ ~ ... (d) ∧ ~ ((∃(s)) student(s) ∧ s.sex = F' ∧ s.deptNo = d.deptId)} None of these
Akriti sood
asked
in
Databases
Dec 2, 2016
by
Akriti sood
1.1k
views
databases
relational-algebra
relational-calculus
4
votes
3
answers
50
tuple relational calculus
Given the following relational schemas Student (studId, name, age, sex, deptNo, advisor) Department (deptId, DName, hod, phoneNo) Which of the following will be the TRC query to obtain the department names that do not have any girl students? 1. {d.Dname | department(d) ∧ ~ ((∃(s)) ... 3. {d.Dname | department(d) ∧ ~ ((∃(s)) student(s) ∧ s.sex = F' ∧ s.deptNo = d.deptId)}
vaishali jhalani
asked
in
Databases
Nov 29, 2016
by
vaishali jhalani
2.1k
views
databases
relational-calculus
1
vote
1
answer
51
How does following SQL translates to relational algebra divide operation?
Book claims that below query translates to relational algebra expression $P/Q$. Can anyone explain how does the below query translates to relational algebra expression $P/Q$? Assume $Q$ has attributes $B_1,B_2,...,B_m$ ... addition the attributes $A_1,A_2,...,A_n$. How above query equates to relation algebra expression $P/Q$?
GateAspirant999
asked
in
Databases
Nov 5, 2016
by
GateAspirant999
990
views
relational-algebra
sql
databases
relational-calculus
4
votes
1
answer
52
Which of the following statements are TRUE/FALSE?
Which of the following statements are TRUE/FALSE? S1: SQL permits attributes names to be repeated in the same relation S2: The power of DRC and TRC is same as that of relational algebra S3: The project operation (pi) cometimes only distributes over join ... (D) <T,F,T> Sol. I dont understand what it is meant by S3. I feel first two are false.
GateAspirant999
asked
in
Programming
Sep 16, 2016
by
GateAspirant999
1.9k
views
relational-calculus
relational-algebra
sql
0
votes
2
answers
53
Which Tuple Relation calculus query is correct?
Schema student (rollNo, name, degree, year, sex, deptNo, advisor) course (courseId, cname, credits, deptNo) enrollment (rollNo, courseId, sem, year, grade) Obtain the names of courses enrolled by student named Mahesh {c.name | course(c) ^ (∃s) (∃e ... (s) ^ c.courseId = e.courseId ^ e.rollNo = s.rollNo ^ s.name = "Mahesh" } Are both correct?
GateAspirant999
asked
in
Databases
Aug 21, 2016
by
GateAspirant999
812
views
databases
relational-calculus
2
votes
0
answers
54
UGC NET CSE | September 2013 | Part 3 | Question: 47
Consider the following schemas: Branch_Schema = (branch_name, assets, city) Customer_Schema = (customer_name, street, city) Deposit_Schema = (branch_name, account_number, customer_name, balance) Borrow_Schema = (branch_name, loan_number, customer_name, amount) Which of the ... { t $\mid$ [?] $\in$ borrow(t(customer_name)[?] s[amount] > 12000}
go_editor
asked
in
Databases
Jul 24, 2016
by
go_editor
775
views
ugcnetcse-sep2013-paper3
databases
relational-calculus
0
votes
1
answer
55
tuple calculas
can anyone provide me best source from where i can learn tuple calculas from starting. thanx in advance
Sourabh Kumar
asked
in
Databases
May 20, 2016
by
Sourabh Kumar
236
views
relational-calculus
1
vote
1
answer
56
Relational Calculus basic
Hi , i have just written the question and answer for the below schema . I have written this according to lectures of IIT KGP . I would request all the experts please look to my solution and point out my mistakes (if any ) :) page 1 Page 2 : page 3 : page 4 :
Dexter
asked
in
Databases
Apr 22, 2016
by
Dexter
548
views
databases
relational-calculus
3
votes
1
answer
57
relational calculus
BOOK(ACC_NO, TITLE, YR_PUB) USER(CARD_NO, B_NAME, B_ADD) B_BY(ACC_NO , CARD_NO , DOI) SUPPLIER(S_NAME,S_ADD) S_BY(S_NAME,S_NAME,PRICE,,DOS) Query :- find the names of those supplier who have supplied titles corresponding to all book issused by 'VIJAY'. using relational calculus solve the query (if possible give proper explation)
indrajeet
asked
in
Databases
Apr 16, 2016
by
indrajeet
834
views
databases
relational-calculus
2
votes
2
answers
58
Tuple Relational Calculus
I believe since the variable 't' is a free variable, so option three should also be right. Second option is also correct?
Utk
asked
in
Databases
Jan 22, 2016
by
Utk
458
views
relational-calculus
databases
1
vote
1
answer
59
Sql and relational algebra
Can anyone suggest me how to learn about sql and relational algebra and calculus for gate? as i feel this is an important topic and one 2 marks ques will be asked. I can understand easy problems and problems with solutions. Anything worth regarding this topic?
khushtak
asked
in
Databases
Jan 20, 2016
by
khushtak
632
views
databases
relational-calculus
relational-algebra
sql
6
votes
4
answers
60
query
Consider the following instance $R$. A 1 2 3 4 B Null 1 2 2 The number of tuples returned by the following SQL query is > select * from $R$ as $R1$ where not exists (select * from $R$ where $B=R1.A$)
resuscitate
asked
in
Databases
Nov 3, 2015
by
resuscitate
605
views
databases
sql
relational-calculus
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