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181

https://gateoverflow.in/1259/gate2007-61
any one can please explain this i.e. this query how it works on a single table i.e. internal mechanism

vcrname9295 asked in Databases Jul 16, 2018

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0 answers

182

Natural Join
Consider two relations R(A, B, C) and S(B, D) with R contains 5000 tuples stored in a sequential file sorted on attribute A and S contain 100000 tuples stored in a sequential file sorted on attribute B. Each block can hold 10 R tuples or 10 S tuples. Which one of the following index is most appropriate for answering query R (natural Join) S (Assume index always stored in memory)

Na462 asked in Databases Jul 14, 2018

by Na462

560 views

0 votes

2 answers

183

Na462 asked in Databases Jul 14, 2018

by Na462

502 views

0 votes

2 answers

184

UGC NET CSE | July 2018 | Part 2 | Question: 62
Consider a relation book (title, price) which contains the titles and prices of different books. Assuming that no two books have the same price, what does the following SQL query? Select title from book as B where (select ... Title of the sixth most expensive books Titles of the seven most expensive books Title of the seventh most expensive books

Pooja Khatri asked in Databases Jul 13, 2018

by Pooja Khatri

1.4k views

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0 answers

185

#DBMS #SQL
For the relations: A(pid, cid) B(pid, pname, powner) C(cid, cname, cdesciption) How will the query be executed : SELECT pname, cname FROM A, B, C WHERE B.powner = $somevalue AND EXISTS(SELECT * FROM A WHERE A.cid = C.cid AND A.pid = B.pid)

Asutosh asked in Databases Jul 7, 2018

130 views

0 votes

1 answer

186

Ace Test Series: DBMS - SQL Query Output

Na462 asked in Databases Jun 29, 2018

by Na462

560 views

1 vote

1 answer

187

SQL Query
Consider relational schema $R(A,B,C)$ and $S(A,B,C)$ $1)$ Select * from $R$ where $(A,B,C)$ in (Select * from $S$) $2)$ Select * from $R$ where exists ( Select * from $S$ where R.A=S.A and R.B=S.B and R.C=S.C) $3)$ Select * from R where $(A,B,C)$ not in((Select * from $R$ where $(A,B,C)$ not in)Select * from S) Which of the following SQL expression equal to $R\cap S$?

srestha asked in Databases Jun 5, 2018

519 views

2 votes

1 answer

188

Database Doubt
Which of the following query results $\text{“all students who never got a grade above 4.0” }$?

Na462 asked in Databases May 26, 2018

by Na462

289 views

0 votes

0 answers

189

Understanding theta join operation
Q.1. Does theta join operator requires following union compatibility requirements?: Same number of columns Domain of corresponding columns should be same I feel no, since I came across following fact: $\sigma_\theta( R_1\times R_2)=R_1⋈_\theta R_2$ ... as shown above, does it mean columns of resultant relation will contain ALL columns from both $R_1$ and $R_2$?

GateAspirant999 asked in Databases May 12, 2018

by GateAspirant999

508 views

0 votes

1 answer

190

SQL Output
Consider the following relational schema

Na462 asked in Databases May 12, 2018

by Na462

252 views

0 votes

1 answer

191

SQL Problem 2
Edges of the directed graph stored in database relation Adj(X, Y) [i.e. if there exists edge from vertex A to B then (A, B) is one record in Adj relation]. Which of the query correct representation to retrieve vertices with only degree two? According to me Both is the Correct answer Please anybody Check

Na462 asked in Databases May 12, 2018

by Na462

240 views

0 votes

0 answers

192

ISI 2017 PCB C3 (B)
Consider the following relations: STD CHOICES (Student ID, Course ID, Semester) and COURSE ASSIGN (Teacher ID, Course ID, Semester). The former indicates the choice of courses for students and the latter indicates the courses assigned to teachers for different ... ID for all the students who have not been taught by the same teacher in more than one course across all semesters.

kapilkant yadav asked in Databases Apr 30, 2018

by kapilkant yadav

198 views

0 votes

1 answer

193

ISI PCB 2017
Consider the following relations: STD CHOICES (Student ID, Course ID, Semester) and COURSE ASSIGN (Teacher ID, Course ID, Semester). The former indicates the choice of courses for students and the latter indicates the courses assigned to teachers for different ... ID for all the students who have not been taught by the same teacher in more than one course across all semesters.

Ajeet Singh asked in Databases Apr 30, 2018

465 views

3 votes

1 answer

194

ISRO2018-40
Given relations $\textsf{R(w,x)}$ and $\textsf{S(y,z)},$ the result of SELECT DISTINCT w, x FROM R, S ls guaranteed to be same as $\text{R},$ if $\textsf{R}$ has no duplicates and $\textsf{S}$ is non-empty $\textsf{R}$ and $\textsf{S}$ have no duplicates $\textsf{S}$ has no duplicates and $\textsf{R}$ is non-empty $\textsf{R}$ and $\textsf{S}$ have the same number of tuples

Arjun asked in Databases Apr 22, 2018

by Arjun

1.5k views

1 vote

1 answer

195

ISRO2018-42
Consider the set of relations given below and the SQL query that follows: Students: (Roll_number, Name, Date_of_birth) Coursed: (Course_number, Course_name, Instructor) Grades: (Roll_number, Course_number, Grade) SELECT DISTINCT Name FROM Students, Courses, Grades WHERE Students. ... have got an $\textsf{A}$ grade in at least one of the courses taught by Sriram None of the above

Arjun asked in Databases Apr 22, 2018

by Arjun

1.4k views

1 vote

1 answer

196

#dbms
emp(eid,ename,age,salary) works(eid,did,pettime) dept(did,dname,budget,managerid) 1.print the names and salary of each employee who works in more than on department. 2.for each department with 15 or more employees,print the department name and the number ... .find the name and age of managers who manage the departments with the largest budgets,and list the related employees in the department.

Naveen Nallanti asked in Databases Mar 29, 2018

by Naveen Nallanti

1.1k views

1 vote

0 answers

197

ISI CSB 2017
Consider the following relational schema: $\text{DOCTOR}(\textit{DoctorName}, \textbf{RegistrationNumber}$) $\text{PATIENT}(\textbf{PatientID}, \textit{PatientName})$ $\text{ASSIGNED-TO}(\textit{ PatientID, DoctorName})$. The primary keys for the DOCTOR and ... calculus expression(or an equivalent SQL query) to find the names of all patients who are assigned to more than one doctor.

shivanisrivarshini asked in Databases Mar 20, 2018

by shivanisrivarshini

907 views

0 votes

0 answers

198

CLustered index
I have read that clustered index is an index on ordered non-key field of DB. However, in SQL clustered index can be created on Primary key. Infact, by default primary key constraint automatically creates clustered index if one doesn't already exists on the table. So, is SQL clustered index different from the one defined in theory?

Nymeria asked in Databases Feb 16, 2018

616 views

19 votes

5 answers

199

GATE CSE 2018 | Question: 12
Consider the following two tables and four queries in SQL. Book (isbn, bname), Stock(isbn, copies) Query 1: SELECT B.isbn, S.copies FROM Book B INNER JOIN Stock S ON B.isbn=S.isbn; Query 2: SELECT B.isbn, S.copies FROM Book B LEFT OUTER JOIN ... is certain to have an output that is a superset of the outputs of the other three queries? Query 1 Query 2 Query 3 Query 4

gatecse asked in Databases Feb 14, 2018

7.8k views

7 votes

2 answers

200

GATE CSE 2001 | Question: 21-b
Consider a relation examinee (regno, name, score), where regno is the primary key to score is a real number. Write an SQL query to list the regno of examinees who have a score greater than the average score.

go_editor asked in Databases Feb 8, 2018

1.4k views

3 votes

1 answer

201

GATE CSE 2001 | Question: 21-c
Consider a relation $\text{examinee (regno, name, score)},$ where regno is the primary key to score is a real number. Suppose the relation $\text{appears (regno, centr_code)}$ specifies the center where an examinee appears. Write an SQL query to list the centr_code having an examinee of score greater than $80.$

go_editor asked in Databases Feb 8, 2018

1.3k views

2 votes

3 answers

202

GATE CSE 1999 | Question: 22-b
Consider the set of relations EMP (Employee-no. Dept-no, Employee-name, Salary) DEPT (Dept-no. Dept-name, Location) Write an SQL query to: Calculate, for each department number, the number of employees with a salary greater than Rs. 1,00,000

go_editor asked in Databases Feb 8, 2018

1.2k views

12 votes

1 answer

203

GATE CSE 1997 | Question: 76-b
Consider the following relational database schema: EMP (eno name, age) PROJ (pno name) INVOLVED (eno, pno) EMP contains information about employees. PROJ about projects and involved about which employees involved in which projects. The underlined attributes are the primary ... makes a copy of $\text{EMP}$ and names it $E$ ($\rho$ is called the rename operator))

go_editor asked in Databases Feb 8, 2018

2.2k views

11 votes

1 answer

204

GATE CSE 1993 | Question: 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 $ \text{*'}.$ ... it is in $\text{3NF}$. If not, normalize the relations so that they are in $\text{3NF}$ (without proving).

go_editor asked in Databases Feb 5, 2018

1.8k views

3 votes

0 answers

205

Interesting question on SQL
Consider a database with three relation instances shown below. The primary keys for the Drivers and Cars relation are did and cid respectively and the records are stored in ascending order of these primary keys as given in the tables. No indexing is available in ... If Binary Search is used to locate a tuple in a relation using primary key, then what is the range of n?

Balaji Jegan asked in Databases Jan 31, 2018

by Balaji Jegan

662 views

4 votes

0 answers

206

srestha asked in Databases Jan 29, 2018

334 views

3 votes

0 answers

207

SQL Query
Why this Query is illigal? i.e. Answer given is option C I tried this on W3school IDE it is giving result as option A.

Ashwin Kulkarni asked in Databases Jan 29, 2018

by Ashwin Kulkarni

308 views

2 votes

2 answers

208

srestha asked in Databases Jan 27, 2018

283 views

1 vote

1 answer

209

MadeEasy Test Series 2018: Databases - Sql

sumit chakraborty asked in Databases Jan 26, 2018

by sumit chakraborty

318 views

1 vote

0 answers

210

SQL....
Why Q1 not correct? Because it is fetching any red part and not every red part,right?? Why Q2 is not correct query? It takes 2 tables and comparing. Is it not fetching single red value?

srestha asked in Databases Jan 25, 2018

321 views

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Recent questions tagged sql