Recent questions tagged relational-calculus

0 votes

1 answer

1

Tuple Relational Calculus - What is the difference between these two types of bounded variables in the expressions?

asked 5 days ago in Databases by tarunmaganti (265 points) | 27 views

+2 votes

1 answer

2

GATE1993-24
The following relations are used to store data about students, courses, enrollment of students in courses and teachers of courses. Attributes for primary key in each relation are marked by *'. Students (rollno*, sname, saddr) courses (cno*, cname) enroll(rollno*, cno*, ... ? If yes, prove that it is in 3 NF. If not normalize, the relations so that they are in 3NF (without proving)?

asked Feb 5 in Databases by jothee Veteran (98.8k points) | 171 views

+2 votes

0 answers

3

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 ?

asked Jan 14 in Programming by ♥_Less Junior (957 points) | 40 views

+1 vote

2 answers

4

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)

asked Jan 2 in Databases by ankit_thawal Active (2.1k points) | 56 views

0 votes

0 answers

5

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)

asked Dec 10, 2017 in Databases by Tuhin Dutta Loyal (7.6k points) | 76 views

0 votes

0 answers

6

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?

asked Dec 10, 2017 in Databases by Tuhin Dutta Loyal (7.6k points) | 51 views

0 votes

0 answers

7

relational calculus

asked Dec 5, 2017 in Databases by Parshu gate Active (4.8k points) | 74 views

+1 vote

1 answer

8

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?

asked Dec 3, 2017 in Databases by learner_geek Active (4.6k points) | 136 views

+2 votes

1 answer

9

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)

asked Dec 3, 2017 in Databases by shaurya vardhan Active (2.2k points) | 105 views

+1 vote

0 answers

10

#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]))}

asked Dec 2, 2017 in Databases by iarnav Loyal (6.5k points) | 29 views

0 votes

1 answer

11

Sql query
Please explain below query step by step and what does it mean?

asked Nov 29, 2017 in Databases by learner_geek Active (4.6k points) | 99 views

+1 vote

0 answers

12

#DBMS Explain these Relational Calculus Queries from GATE Question!

asked Nov 29, 2017 in Databases by iarnav Loyal (6.5k points) | 115 views

0 votes

1 answer

13

TUPLE CALCULUS

asked Nov 6, 2017 in Databases by Parshu gate Active (4.8k points) | 83 views

+2 votes

0 answers

14

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

asked Oct 3, 2017 in Databases by Venkat Sai Active (3.1k points) | 73 views

+2 votes

1 answer

15

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

asked Aug 26, 2017 in Databases by Tushar Pandey (31 points) | 180 views

+1 vote

0 answers

16

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.

asked Jul 16, 2017 in Databases by shashank023 (417 points) | 103 views

+18 votes

4 answers

17

GATE2017-1-41
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. {$t$ | $\exists$u $ ... ))} Which of the above queries are safe? I and II only I and III only II and III only I, II and III

asked Feb 14, 2017 in Databases by Arjun Veteran (339k points) | 3.2k views

+1 vote

1 answer

18

Mock Test
Is statement 1 true for all safe expressions ?

asked Jan 24, 2017 in Databases by Harsh181996 Active (3.9k points) | 246 views

+1 vote

1 answer

19

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)

asked Jan 14, 2017 in Databases by Geet (247 points) | 153 views

0 votes

0 answers

20

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

asked Dec 2, 2016 in Databases by Akriti sood Boss (13.5k points) | 182 views

0 votes

1 answer

21

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)}

asked Nov 29, 2016 in Databases by vaishali jhalani Loyal (5.8k points) | 338 views

+1 vote

1 answer

22

How does following SQL translates to relational algebra divide operation?

asked Nov 5, 2016 in Databases by GateAspirant999 Active (2.5k points) | 192 views

+3 votes

1 answer

23

Which of the following statements are TRUE/FALSE?

asked Sep 16, 2016 in Programming by GateAspirant999 Active (2.5k points) | 425 views

0 votes

2 answers

24

Which Tuple Relation calculus query is correct?

asked Aug 21, 2016 in Databases by GateAspirant999 Active (2.5k points) | 179 views

0 votes

1 answer

25

tuple calculas
can anyone provide me best source from where i can learn tuple calculas from starting. thanx in advance

asked May 20, 2016 in Databases by Sourabh Kumar Active (1.8k points) | 103 views

+1 vote

1 answer

26

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 :

asked Apr 22, 2016 in Databases by Dexter Loyal (9.6k points) | 257 views

+1 vote

1 answer

27

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)

asked Apr 16, 2016 in Databases by indrajeet Active (1.9k points) | 174 views

+1 vote

2 answers

28

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?

asked Jan 22, 2016 in Databases by Utk Active (2.1k points) | 176 views

+1 vote

1 answer

29

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?

asked Jan 20, 2016 in Databases by khushtak Loyal (7.5k points) | 308 views

+6 votes

4 answers

30

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 $B=R1.A$)

asked Nov 3, 2015 in Databases by resuscitate Loyal (6.5k points) | 233 views

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