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. UNIQUE

C. PRIMARY KEY

D. NOT NULL

Answer: Option D

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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What is the purpose of the SQL 'CONSTRAINT' keyword?

A. To create views

B. To create indexes

C. To join tables

D. To define rules for data integrity

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Correct Answer: Option D

Explanation:
Constraints are used to enforce rules on data, such as NOT NULL, UNIQUE, PRIMARY KEY, FOREIGN KEY, and CHECK.

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

Question #2

What is the purpose of the SQL 'JOIN' clause?

A. To create a new table

B. To delete records from a table

C. To combine rows from two or more tables based on a related column

D. To combine columns from multiple tables into a single table

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Correct Answer: Option C

Explanation:
JOIN is used to combine rows from different tables based on a common column, allowing querying across related tables.

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

Question #3

In SQL, which statement is used to create a new database?

A. NEW DATABASE

B. CREATE DATABASE

C. CREATE SCHEMA

D. CREATE TABLE

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Correct Answer: Option B

Explanation:
CREATE DATABASE is used to create a new database in SQL.

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

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