CBSE Class 12 Computer Science Database Concepts MCQs Set B

Question. In files, there is a key associated with each record which is used to differentiate among different records. For every file, there is atleast one set of keys that is unique. Such a key is called
(a) unique key
(b) prime attribute
(c) index key
(d) primary key

Answer : D

Question. Which of the following is not a DBMS?
(a) MS-Word
(b) MySQL
(c) Oracle
(d) Microsoft SQL Server

Answer : A

Question. The total number of rows in a table is called
(a) domain
(b) tuple
(c) field
(d) cardinality

Answer : D

Question. Which of the following is the drawback of DBMS?
(a) Improvement in data
(b) Backup and recovery
(c) Complexity
(d) Maintenance of data integrity

Answer : C

Question. In a relational data model, a data structure that organises the information about a single topic into rows and columns is
(a) block
(b) record
(c) tuple
(d) table

Answer : D

Question. Tables can be linked by
(a) primary key
(b) candidate key
(c) alternate key
(d) foreign key

Answer : D

Question. Raj wants to make EmpNo and PFNo columns of his table as the primary key. Is it possible?
(a) Yes
(b) No
(c) Yes , possible as a comination of columns
(d) None of the above

Answer : C

Question. The total number of columns in a table is called
(a) cardinality
(b) degree
(c) spreadsheet
(d) relation

Answer : B

Question. The attributes which have all the properties of primary key
(a) Foreign key
(b) Alternate key
(c) Candidate key
(d) Both (a) and (c)

Answer : C

Question. Which of the following was the first network database?
(a) SYSTEM 2000
(b) DBTG CODASYL
(c) SYSTEM CODASYL
(d) DBTG 2000

Answer : B

Question. Which of the following are used in data definition?
(a) DML
(b) DDL
(c) TCL
(d) None of these

Answer : B

Question. The design of the database is known as what?
(a) Attribute
(b) database schema
(c) obstruction
(d) database oriented

Answer : B

Assertion and Reason Based MCQs

Directions : In the following questions, A statement of Assertion (a) is followed by a statement of Reason (R). Mark the correct choice as.
(a) Both A and R are true and R is the correct explanation for A.
(b) Both A and R are true and R is not correct explanation for A.
(c) A is true but R is false.
(d) A is false but R is true.

Question. Assertion (A): A referential integrity is a system of rules of DBMS.
Reason (R): It ensures that user don’t accidently delete or change related data.

Answer : A

Question. Assertion (A): The keyword DISTINCT is used with SELECT command.
Reason (R): DISTINCT keyword eliminates duplicate rows.

Answer : A

Question. Assertion (A): CHAR and VARCHAR both are used to store integer values.
Reason (R): CHAR is fixed length and VARCHAR is of variable length.

Answer : D

Question. Assertion (A): Recording of relationship implementation in network model is very complex since pointers are used.
Reason (R): DBTG codasyl was the first network database.

Answer : B

Question. Assertion (A): TCL stands for Transaction Control Language.
Reason (R): These commands perform retrieval, insertion, deletion and modification etc. on databases.

Answer : C

Question. Assertion (A): Cartesian product is a Cross Join
Reason(R): An SQL Join query joins tables on condition basis.

Answer : B

Question. Assertion (A): A database consists of a number of tables.
Reason (R): Each table comprises of rows and records.

Answer : C

Case-based MCQs

Attempt any 4 sub-parts from each question. Each subpart carries 1 mark.
I. Mr. Sumit Agarwal is the owner of his parental firm Ramdas Gopal das & Sons which deals in the wholesale business of spices.
He wants to maintain records of spices available in their shop and generate bills when someone purchases any spices from the shop.
They want to create a database to keep track of all the spices in the shop and the spices purchased by customers.

Question. To add records in the table which of the following SQL statement is used?
(a) ADD
(b) SELECT
(c) INSERT
(d) INSERT INTO

Answer : D

Question. Which is the correct SQL statement to create the table?
(a) CREATE TABLE spice(scode integer, sname char(25), price decimal, stock integer)
(b) CREATE spice(scode integer, sname char(25), price decimal, stock integer)
(c) CREATE TABLE spice(scode , sname , price, stock)
(d) SELECT TABLE spice(scode integer, sname char(25), price decimal, stock integer)

Answer : A

Question. To add a new column exp_date in the existing table the statement is
(a) ALTER TABLE spice ADD (exp_date date)
(b) UPDATE TABLE spice ADD (exp_date date)
(c) MODIFY spice ADD (exp_date date)
(d) ALTER TABLE spice MODIFY (exp_date date)

Answer : A

Question. To create an index on name of spices in the existing table, the command is
(a) ALTER TABLE spice ADD INDEX spice_idx (sname)
(b) CREATE INDEX spice_idxON spice (sname)
(c) CREATE TABLE spice (INDEX spice_idx (sname))
(d) Both (a) and (b)

Answer : D

Question. To view the table structure of the above crated table the command is
(a) SELECT spice
(b) DESC spice
(c) DESCRIBE spice
(d) Both (b) and (c)

Answer : D
 

Consider the table STUDENT with following details.

Question. View all records other than ‘12A’ class
(a) SELECT DISTINCT CLASS FROM STUDENT
(b) SELECT CLASS FROM STUDENT WHERE (CLASS NOT = ‘Science’)
(c) SELECT * FROM STUDENT WHERE CLASS NOT IN (‘Science’)
(d) None of these

Answer : C

Question. Command to select all Science students from the table STUDENT
(a) SELECT * FROM STUDENT
(b) SELECT STREAM FROM STUDENT WHERE STREAM= ‘Science’
(c) SELECT * FROM STUDENT WHERE STREAM = ‘Science’
(d) SELECT NAME FROM STUDENT WHERE STREAM = ‘Science’

Answer : C

Question. Modify the marks of Aastha as 85.5
(a) ALTER TABLE STUDENT SET MARKS = 85.5 WHERE NAME = ‘Aastha’
(b) UPDATE STUDENT SET MARKS = 85.5 WHERE NAME=’Aastha’
(c) UPDATE TABLE STUDENT SET MARKS = 85.5 WHERE NAME=’Aastha’
(d) ALTER STUDENT SET MARKS=85.5 WHERE NAME = Aastha’

Answer : B

Question. Add a record of new student ‘Geeta’ of ‘Commerce’ stream in class ‘12B’ and her marks is ‘78.9’.
(a) INSERT INTO STUDENT VALUES (‘Geeta’, ‘Commerce’, ‘12B’, 78.9)
(b) INSERT INTO STUDENT VALUES (7, ‘Geeta’, ‘Commerce’, ‘12B’, 78.9)
(c) INSERT INTO STUDENT VALUES (‘Geeta’, ‘Commerce’, 78.9, ‘12B’)
(d) INSERT INTO STUDENT VALUES (7, ‘Geeta’, ‘Commerce’, 78.9, ‘12B’)

Answer : D

Question. Delete records that belongs to ‘Humanities’ stream
(a) DELETE FROM STUDENT WHERE STREAM = ‘Humanities’
(b) DROP FROM STUDENT WHERE STREAM = ‘Humanities’
(c) DROP TABLE STUDENT WHERE STREAM = ‘Humanities’
(d) None of these

Answer : A

Mr. Sharma is a new user of database systems. He has created a table storing the details of staff in his office. He is confused about some of the terms related to tables and databases. Help him solving his confusions.

Question. An attribute which can uniquely identify tuples of the table but is not defined as primary key of the table is called
(a) primary key
(b) alternate key
(c) forign key
(d) None of these

Answer : B

Question. What is the cardinality of the table?
(a) 2
(b) 3
(c) 4
(d) 1

Answer : C

Question. The vertical set storing the departments under the heading 'Dept' is called
(a) field
(b) attribute
(c) column
(d) All of these

Answer : D

Question. A tuple carries
(a) a single value
(b) double values
(c) a row of multiple values as a record
(d) None of the above

Answer : C

Question. Can 'StaffName' column serve as primary key?
(a) No
(b) Yes, only if it stores non-blank and distinct names
(c) Yes, only if it stores only distinct names
(d) Yes

Answer : B