Which constraint ensures that a column cannot have NULL values? MCQ with Answer and Explanation

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Which constraint ensures that a column cannot have NULL values?

A. FOREIGN KEY

B. NOT NULL

C. UNIQUE

D. PRIMARY KEY

Answer: Option B

Solution (By JKSSB Mock Tests)

NOT NULL constraint enforces that a column must have a value, preventing NULL entries.

This question belongs to: Computer Database Management System (DBMS)

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Practice More Database Management System (DBMS) Questions

Question #1

Which SQL command is used to add new rows of data into an existing table?

A. APPEND

B. UPDATE

C. ADD

D. INSERT

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Correct Answer: Option D

Explanation:
The INSERT command is a Data Manipulation Language (DML) statement used to add new records/rows to a table.

This question belongs to: Computer Database Management System (DBMS)

Question #2

Which of the following is a method to avoid deadlock?

A. Deadlock detection and resolution

B. All of the above

C. Using a timeout

D. Lock ordering

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Correct Answer: Option B

Explanation:
Strategies to handle deadlocks include timeout, lock ordering, and detection with rollback.

This question belongs to: Computer Database Management System (DBMS)

Question #3

Which language category in SQL is used by database administrators to grant and revoke access privileges and security permissions?

A. DCL

B. TCL

C. DML

D. DDL

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Correct Answer: Option A

Explanation:
Data Control Language (DCL) includes commands like GRANT and REVOKE, which manage privileges and security configurations for database users.

This question belongs to: Computer Database Management System (DBMS)

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