List of Top DBMS Questions on SQL asked in UGC NET

Which of the following command can be used to modify data in an SQL Table?

A. INSERT

B. DELETE

C. UPDATE

D. SELECT

Choose the correct answer from the options given below:

What is SQL primarily used for in the context of relational databases ?

INSERT command is used to

A. add a single tuple to a relation

B. add multiple tuples to a relation

C. add values to specific attributes

D. insert new table

Choose the correct answer from the options given below:

Given query:

select s.rollno, s.name

from student s

where EXISTS (select c.courseid from course c Where c.deptno=5 and

EXISTS (select e.* from enrollemnt e

where e.courseid = c.courseid and

e.rollno = s.rollno));

Which one of the following statements is correct with respect to the given query?

Which of the following queries would retrieve the dept id and name of all the departments that are such that the total of the credits of all the offered courses by the department is strictly greater than 40?

Which of the following queries would compute, for each department, the total credits of all the courses offered by the department?

Given query: select s.rollno from students where s.sex = ALL (select f.sex from professor f where f.empid = s.advisor)

Consider the following statements about the given query that retrieves the set of all students whose gender is same as the gender of their advisor:

S1. It has a correlated subquery

S2. It has an uncorrelated subquery

S3. If we replace ALL by ANY in the above query, its result will be different

S4. If we replace ALL by ANY in the above query, its result will be same.

Identify all the statement that are TRUE:

Which of the following queries would retrieve the roll number and names of students who have enrolled for all the prerequisite courses of the course number 324?

Consider the following ORACLE relations :

R (A, B, C) = {<1, 2, 3>, <1, 2, 0>, <1, 3, 1>, <6, 2, 3>, <1, 4, 2>, <3, 1, 4> }

S (B, C, D) = {<2, 3, 7>, <1, 4, 5>, <1, 2, 3>, <2, 3, 4>, <3, 1, 4>}.

Consider the following two SQL queries SQ₁ and SQ₂ :

SQ₁ : SELECT R⋅B, AVG (S⋅B)

      FROM R, S

      WHERE R⋅A = S⋅C AND S⋅D < 7

      GROUP BY R⋅B;

SQ₂ : SELECT DISTINCT S⋅B, MIN (S⋅C)

      FROM S

      GROUP BY S⋅B

      HAVING COUNT (DISTINCT S⋅D) > 1;

If M is the number of tuples returned by SQ₁ and N is the number of tuples returned by SQ₂ then

Consider the following relation :

Works (emp_name, company_name, salary)

Here, emp_name is primary key.

Consider the following SQL query

    Select emp_name

    From works T

    where salary > (select avg (salary)

                    from works S

                    where T.company _ name =

                        S.company _ name)

The above query is for following :