Top 1000+ Solved DataBase Management System (DBMS) MCQ Questions Answer

From 1156 to 1170 of 1187

Q. The primary key must be

a. unique

b. not null

c. both unique and not null

d. either unique or not null

  • c. both unique and not null

Q. The result of           unknown is unknown.

a. xor

b. or

c. and

d. not

  • d. not

Q. Aggregate functions are functions that take a                        as input and return a single value.

a. collection of values

b. single value

c. aggregate value

d. both collection of values & single value

  • a. collection of values

Q. Which of the following is not an aggregate function?

a. avg

b. sum

c. with

d. min

  • c. with

Q. The EXISTS keyword will be true if:

a. any row in the subquery meets the condition only

b. all rows in the subquery fail the condition only

c. both of these two conditions are met

d. neither of these two conditions is met

  • a. any row in the subquery meets the condition only

Q. Which one of the following deletes all the entries but keeps the structure of the relation.

a. delete from r where p;

b. delete from instructor where dept name= ’finance’;

c. delete from instructor where salary between 13000 and 15000;

d. delete from instructor;

  • d. delete from instructor;

Q. Which of the join operations do not preserve non matched tuples?

a. left outer join

b. right outer join

c. inner join

d. natural join

  • c. inner join
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