CBSE Class 12 Computer Science Database Concepts MCQs Set A

Question. A relational database is a collection of
(a) Attributes
(b) Tables
(c) Records
(d) Fields

Answer : B

Question. ____________ refers to the attribute that can uniquely identify tuples within the relation.
(a) Foreign key
(b) Consolidate key
(c) Alternate Key
(d) Primary key

Answer : D

Question. An Alternate key can be defined as
(a) An attribute which is a primary key
(b) An attribute which is not a primary key
(c) A candidate key
(d) None of these

Answer : B

Question. Consider a table with following structure: Employee(Emp_id, Emp_name, Dept, Desig, basic) In this table which attribute can be used as a primary key?
(a) Emp_id
(b) Emp_name
(c) Dept
(d) Desig

Answer : A

Question. An attribute whose value is derived from the primary key of some other table.
(a) Primary key
(b) Foreign key
(c) Alternate key
(d) None of these

Answer : B

Question. Each table comprises of ______ and ________ .
(a) rows, columns
(b) data, information
(c) database, table
(d) None of these

Answer : A

Question. How many rules were laid down by E.F Codd?
(a) 10
(b) 11
(c) 12
(d) 13

Answer : C

Question. DBMS stands for
(a) Database Microsoft System
(b) Database Migration System
(c) Database Management System
(d) None of the above

Answer : C

Question. If we delete an attribute of a table
(a) degree increases
(b) cardinality increases
(c) degree and cardinality increase
(d) degree decreases

Answer : D

Question. A table can have ………… primary key(s).
(a) 1
(b) 2
(c) 3
(d) multiple

Answer : A

Question. Software that is used to create , manipulate , maintain a relational database management system is called
(a) documentation software
(b) spreadsheet software
(c) RDBMS
(d) designing software

Answer : C

Question. Which of the following component of database system consists of various secondary storage devices on which data is stored?
(a) Hardware
(b) User
(c) Data
(d) Software

Answer : A

Question. A field of a table is termed as __________.
(a) Row
(b) Attribute
(c) Key
(d) Tuple

Answer : B

Question. A RDBMS must comply with at least _______ rules.
(a) 4
(b) 5
(c) 6
(d) 7

Answer : C

Question. A tuple in RDBMS is referred to _________ of a table.
(a) Record
(b) Field
(c) Table
(d) Key

Answer : A

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): INSERT command is an SQL command.
Reason (R): NOT NULL constraint ensures that a column cannot have a NULL value.

Answer : B

Question. Assertion (A): The data in a table once added can be modified later.
Reason (R): ALTER TABLE command is used to modify table structure.

Answer : B

Question. Assertion (A): UNIQUE constraint holds same value for the column.
Reason (R): There can be multiple UNIQUE constraints.

Answer : D

Question. Assertion (A): In hierarchical model, searching for a record is very time consuming.
Reason (R): The data is organised in a tree structure

Answer : A

Question. Assertion (A): The columns that are not PRIMARY should have FOREIGN KEY constraint.
Reason (R): Referential integrity is ensured through FOREIGN KEY.

Answer : A

Question. Assertion (A): Indexes can be created at the time of table creation.
Reason (R): By default indexes are in descending order.

Answer : C

Case Based MCQs :

Anita has created a table 'Players' to store the details of players who play in her sports academy. She has planned to create the following table with columns :
PlayerId, PlayerName , Game, Type , AadharNo

Answer the following questions, which based on the given information.

Question. Which column(s) can act as candidate key?
(a) Only PlayerId
(b) Only AadharNo
(c) Both (a) and (b)
(d) Type

Answer : C

Question. What is the degree of the table?
(a) 1
(b) 2
(c) 3
(d) 5

Answer : D

Question. Which column can she make the primary key?
(a) PlayerId
(b) PlayerName
(c) Game
(d) Type

Answer : A

Question. What will be the cardinality of the table, if two columns are added to the table?
(a) 7
(b) 6
(c) 4
(d) None of these

Answer : C

Question. Which column is the foreign key in the table?
(a) PlayerName
(b) Type
(c) Game
(d) None of these

Answer : D

Consider the following SQL command:
CREATE TABLE MEMBER
( MEM_ID INTEGER NOT NULL,
NAME CHAR(15) NOT NULL,
DATE_JOIN DATE,
SEX CHAR(1) CHECK (SEX= ‘M’ OR SEX = ‘F’),
ADDRESS VARCHAR(100) NOT NULL,
PH_NO CHAR(15),
PRIMARY KEY (MEM_NO),
INDEX MEM_IDX (DATE_JOIN)
);
Now answer the following questions:

Question. The INDEX command in above example will
(a) Create an index on field DATE_JOIN
(b) Create an index namely MEM_IDX
(c) Both (a) and (b)
(d) None of the above

Answer : C

Question. NOT NULL ensures that
(a) Column cannot have blank value
(b) Column will not accept any value
(c) Column has a fixed value
(d) Column has a unique value

Answer : A

Question. The ______ constraint ensures that the value entered specifies a certain condition.
(a) NOT NULL
(b) NULL
(c) CHECK
(d) All of these

Answer : C

Question. By default format of date entered is
(a) DD-MM-YY
(b) MM-DD-YY
(c) YYYY-MM-DD
(d) DD-MM-YYYY

Answer : C

Question. PRIMAY KEY in above example ensures that
(a) MEM_ID is entered primarily
(b) MEM_ID will hold a uniquely identified value
(c) MEM_ID will not remain blank
(d) All of these

Answer : D