Database Management Class 12 Computer Science Board Paper MCQ

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Prepare for your Class 12 Computer Science Board Examination with these Database Management MCQs. This collection includes important multiple-choice questions based on key concepts of database management and the CBSE Class 12 Computer Science syllabus. Students can use these questions to revise important topics, improve their understanding, and practise questions in a board-exam pattern.

Regular practice of Class 12 Computer Science Database Management MCQs can help students identify weak areas, improve accuracy, and build confidence before the examination.

Database Management Class 12 Computer Science Board Paper MCQ

Q. State True or False : In SQL, the UNIQUE constraint on an attribute ensures that values in it are not left empty.

Answer: False (UNIQUE does not prevent NULL values)

Q. The degree of the resulting relation after the Cartesian Product of two SQL tables with degrees A and B will be :
(A) A x B
(B) A + B
(C) A – B
(D) A / B

Answer: (B) A + B

Q. Which of the following is not true about SQL?
(A) SQL is case sensitive.
(B) An SQL statement will always end with a colon (:).
(C) SQL stands for Structured Query Language.
(D) SQL is used to retrieve data from tables through queries.

Answer: (A) SQL is case sensitive.

Q. Which of the following is used to add a primary key to a column in a table created in MySQL?
(A) INSERT
(B) MODIFY
(C) UPDATE
(D) ALTER

Answer: (D) ALTER

Q. In MySQL, which of the following operator is used with WHERE clause and returns a True if the value belongs to the set of specified values?
(A) DISTINCT
(B) IN
(C) LIKE
(D) NOT

Answer: (B) IN

Q. Assertion (A) : If we define an attribute of a table as a Foreign key, then UNIQUE and NOT NULL constraints are automatically applied to it.
Reason (R) : The Foreign key column of a table takes its values from the Primary key of another table.
(A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
(C) Assertion (A) is true, but Reason (R) is false.
(D) Assertion (A) is false, but Reason (R) is true.

Answer: (D) Assertion (A) is false, but Reason (R) is true.

Q. A table has two candidate keys, one of which is chosen as the primary key. How many alternate keys does this table have?
(A) 0
(B) 1
(C) 2
(D) 3

Answer: (B) 1

Q. Which of the following SQL command can change the degree of the existing relation?
(A) DROP TABLE
(B) ALTER TABLE
(C) UPDATE…SET
(D) DELETE

Answer: (B) ALTER TABLE

Q. What will be the output of the query?
SELECT MACHINE_ID, MACHINE_NAME FROM INVENTORY WHERE QUANTITY <= 100;
(A) All columns of INVENTORY table with quantity greater than 100
(B) ID and name of machines with quantity less than 100 from INVENTORY table
(C) All columns of INVENTORY table with quantity greater than or equal to 100
(D) ID and name of machines with quantity less than or equal to 100 from INVENTORY table.

Answer: (D) ID and name of machines with quantity less than or equal to 100 from INVENTORY table.

Q. A relation in MySQL database consists of 2 tuples and 3 attributes. If 2 attributes are deleted and 4 tuples are added, what will be the cardinality of the relation?
(A) 4
(B) 5
(C) 6
(D) 7

Answer: (C) 6

Q. Which aggregate function in SQL returns the smallest value from a column in a table?
(A) MIN()
(B) MAX()
(C) SMALL()
(D) LOWER()

Answer: (A) MIN()

Q. Write any two DDL commands.

Answer: CREATE, ALTER (or DROP, TRUNCATE)

Q. Which of the following is not a valid relational operator used with WHERE clause in SQL?
(A) >
(B) <=
(C) =>
(D) <>

Answer: (C) =>

Q. What is the default format of date in MySQL?
(A) DD-MM-YYYY
(B) MM-DD-YYYY
(C) YYYY-MM-DD
(D) YYYY-DD-MM

Answer: (C) YYYY-MM-DD

Q. Ginni has created a table, SCORES in MySQL to store runs scored by players in a cricket match. The table contains the following records :

Table : Scores

Which of the following statements will give 10 as output?
(A) SELECT MAX(Score) FROM Scores;
(B) SELECT MIN(Score) FROM Scores;
(C) SELECT SUM(Score) FROM Scores;
(D) SELECT AVG(Score) FROM Scores;

Answer: (B) SELECT MIN(Score) FROM Scores;

Q. Assertion (A) : Foreign key column of a table cannot have NULL entries.
Reason (R) : Primary key column of a table cannot have NULL entries.
(A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
(C) Assertion (A) is true, but Reason (R) is false.
(D) Assertion (A) is false, but Reason (R) is true.

Answer: (D) Assertion (A) is false, but Reason (R) is true.

Q. The primary key is selected from the set of ___________ .
(A) composite keys
(B) alternate keys
(C) candidate keys
(D) foreign keys

Answer: (C) candidate keys

Q. In SQL, which command will be used to add a new record in a table?
(A) UPDATE
(B) ADD
(C) INSERT
(D) ALTER TABLE

Answer: (C) INSERT

Q. Mr. Ravi is creating a field that contains alphanumeric values and fixed lengths. Which MySQL data type should he choose for the same?
(A) VARCHAR
(B) CHAR
(C) LONG
(D) NUMBER

Answer: (B) CHAR

Q. Fill in the blank : In a relational model, tables are called _________, that store data for
different columns.
(a) Attributes
(b) Degrees
(c) Relations
(d) Tuples

Answer: (c) Relations

Q. Fill in the blank : _________ statement of SQL is used to insert new records in a table.
(a) ALTER
(b) UPDATE
(c) INSERT
(d) CREATE

Answer: (c) INSERT

Q. While creating a table, which constraint does not allow insertion of duplicate values in the table?
(A) UNIQUE
(B) DISTINCT
(C) NOT NULL
(D) HAVING

Answer: (A) UNIQUE

Q. Which of the following is a DML command in SQL?
(A) UPDATE
(B) CREATE
(C) ALTER
(D) DROP

Answer: (A) UPDATE

Q. Which aggregate function in SQL displays the number of values in the specified column ignoring the NULL values?
(A) 1len()
(B) count()
(C) number ()
(D) num()

Answer: (B) count()

Q. In MYSQL, which type of value should not be enclosed within quotation marks?
(A) DATE
(B) VARCHAR
(C) FLOAT
(D) CHAR

Answer: (C) FLOAT

Q. State True or False : If table A has 6 rows and 3 columns, and table B has 5 rows and 2 columns, the Cartesian product of A and B will have 30 rows and 5 columns.

Answer: True (30 rows and 5 columns)

Q. Assertion (A) : We can retrieve records from more than one table in MYSQL.
Reason (R) : Foreign key is used to establish a relationship between two tables.
(A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation for Assertion (A).
(B) Both Assertion (A) and Reason (R) are true and Reason (R) is not the correct explanation for Assertion (A).
(C) Assertion (A) is true but, Reason (R) is false.
(D) Assertion (A) is false but, Reason (R) is true.

Answer: (B) Both Assertion (A) and Reason (R) are true and Reason (R) is not the correct explanation for Assertion (A).

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