1
GATE CSE 2015 Set 1
Numerical
+2
-0

Consider the following relation:

Student

Roll_No Student_Name
1 Raj
2 Rohit
3 Raj

Performance

Roll_No Course Marks
1 Math 80
1 English 70
2 Math 75
3 English 80
2 Physics 65
3 Math 80

Consider the following SQL query.

SELECT S.Student_Name, Sum(P.Marks)
FROM Student S, Performance P
WHERE S.Roll_No= P.Roll_No
GROUP BY S.STUDENT_Name
The numbers of rows that will be returned by the SQL query is___________.
2
GATE CSE 2014 Set 1
+2
-0.6

Given the following schema:

employees(emp-id, first-name, last-name, hire-date, dept-id, salary)

departments(dept-id, dept-name, manager-id, location-id)

You want to display the last names and hire dates of all latest hires in their respective departments in the location ID 1700. You issue the following query:
SQL> SELECT last-name, hire-date
FROM employees WHERE (dept-id, hire-date) IN
(SELECT dept-id, MAX(hire-date)
FROM employees JOIN departments USING(dept-id)
WHERE location-id = 1700
GROUP BY dept-id);
What is the outcome?
A
It executes but does not give the correct result.
B
It executes and gives the correct result.
C
It generates an error because of pairwise comparison.
D
It generates an error because the GROUP BY clause cannot be used with table joins in a sub-query.
3
GATE CSE 2014 Set 3
+2
-0.6

Consider the following relational schema:

employee (empId, empName, empDept )

customer (custId, custName, salesRepId, rating)

SalesRepId is a foreign key referring to empId of the employee relation. Assume that each employee makes a sale to at least one customer. What does the following query return?
SELECT empName
FROM employee E
WHERE NOT EXISTS (SELECT custId
FROM customer C
WHERE C.salesRepId = E.empId
AND C.rating <> 'GOOD');
A
Names of all the employees with at least one of their customers having a 'GOOD' rating.
B
Names of all the employees with at most one of their customers having a 'GOOD' rating.
C
Names of all the employees with none of their customers having a 'GOOD' rating.
D
Names of all the employees with all their customers having a 'GOOD' rating.
4
GATE CSE 2014 Set 2
+2
-0.6
SQL allows duplicate tuples in relations, and correspondingly defines the multiplicity of tuples in the result of joins. Which one of the following queries always gives the same answer as the nested query shown below:
Select * from R where a in (select S.a from S)
A
Select R.* from R, S where R.a = S.a
B
Select distinct R.* from R, S where R.a = S.a
C
Select R.* from R, (select distinct a from S) as S1 where R.a = S1.a
D
Select R.* from R, S where R.a = S.a and is unique R
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