Introduction to Database Systems Week 6 Quiz Answers Nptel
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Introduction to Database Systems Week 6 Quiz Answers (Jan-Apr 2025)
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- Under which of the following conditions are update operations on views NOT allowed?
a) Only (ii)
b) Only (iii)
c) Only (i) and (ii)
d) All (i), (ii), and (iii)
- HAVING clause can be used in a query only if GROUP BY clause is used
a) True
b) False
- GROUP BY clause can be used in a query only if HAVING clause is used
a) True
b) False
- It is mandatory to use an aggregate function in a query if GROUP BY clause is used
a) True
b) False
- Aggregate functions can be used in GROUP BY clauses
a) True
b) False
- In which of the following SQL clauses of a main query can a sub-query be made use of?
a) Only (ii)
b) Only (iii)
c) Only (ii) and (iii)
d) All (i), (ii), and (iii)
- Which of the following queries would select the courses with at least 10 ‘W’ grades in some offering of the course?
a) SELECT courseId FROM enrollment WHERE grade = ‘W’ GROUP BY courseId HAVING count(rollNo) >= 10
b) SELECT courseId FROM enrollment WHERE grade = ‘W’ GROUP BY courseId, sem, year HAVING count(rollNo) >= 10
c) SELECT courseId FROM enrollment WHERE grade = ‘W’ AND count(rollNo) >= 10 GROUP BY courseId
d) SELECT courseId FROM enrollment WHERE grade = ‘W’ AND count(rollNo) >= 10 GROUP BY courseId, sem, year
- Which of the following queries will retrieve students whose name has ‘p’ as the second letter?
a) SELECT rollNo FROM student WHERE name = ‘_p’;
b) SELECT rollNo FROM student WHERE name LIKE ‘_p’;
c) SELECT rollNo FROM student WHERE name LIKE ‘_p%’;
d) SELECT rollNo FROM student WHERE name IN ‘_p%’;
- Consider two instances of the relations R1(A, B) and R2(C, D) with the number of rows 10 and 8, respectively. What is the least possible number of tuples in the result of the following query?
SELECT * FROM R1 FULL OUTER JOIN R2 ON R1.A = R2.C
a) 0
b) 18
c) 8
d) 10
- Which of the following queries is correct to find the courses with no prerequisites?
a) SELECT courseId FROM preRequisite GROUP BY courseId HAVING count(preCourseId) = 0
b) SELECT courseId FROM preRequisite a WHERE NOT EXISTS (SELECT preCourseId FROM preRequisite b WHERE a.courseId = b.courseId)
c) Both (i) and (ii)
d) Neither (i) nor (ii)
- Which of the following queries would find the ID and name of the senior-most HOD(s)?
a) SELECT p1.empId, p1.name FROM professor p1 WHERE p1.startYear IN (SELECT min(p.startYear) FROM professor p, department d WHERE p.empId = d.hod)
b) SELECT p.empId, p.name FROM professor p, department d WHERE p.empId = d.hod WHERE p.startYear IN (SELECT min(p1.startYear) FROM professor p1)
c) SELECT p1.empId, p1.name FROM professor p1, department d1 WHERE p1.empId = d1.hod AND p1.startYear IN (SELECT min(p.startYear) FROM professor p, department d WHERE p.empId = d.hod)
d) None of the above
- Which one of the following queries would find the teacher(s) who taught CS1100 the highest number of times?
a)
CREATE VIEW EmpCount AS
SELECT empId, count(*) AS cnt
FROM teaching
WHERE courseId = ‘CS1100’
GROUP BY empId;
SELECT empId FROM EmpCount WHERE cnt = (SELECT MAX(cnt) from EmpCount);
b)
CREATE VIEW EmpCount AS
SELECT empId, count(*) AS cnt
FROM teaching
WHERE courseId = ‘CS1100’;
SELECT empId FROM EmpCount WHERE cnt = (SELECT MAX(cnt) from EmpCount);
c)
SELECT empId, max(count(*)) AS cnt
FROM teaching
WHERE courseId = ‘CS1100’
GROUP BY empId;
d)
SELECT empId
FROM teaching
WHERE courseId = ‘CS1100’
GROUP BY empId
HAVING COUNT(*) = (SELECT max(count(*)) FROM teaching WHERE courseId = ‘CS1100’);
- Consider the following sets about different approaches to programmatic access of databases and the properties that may apply to these approaches.
{1: Embedded SQL approach; 2: API based approach; 3: Database language approach}{p: Only one connection to a DB server can be active at any time q: Open Database Connectivity (ODBC); r: Cursors; s: Programmers need to learn a new language ; t: Multiple connections to DB servers can be active at any time}
Identify the correct matching between the sets:
a) 1–p; 2–t; 3–q
b) 1–t; 2–q; 3–s
c) 1–s; 2–r; 3–p
d) 1–p; 2–t; 3–s
Introduction to Database Systems Week 6 Quiz Answers
For answers to others Nptel courses, please refer to this link: NPTEL Assignment
