Which of the following is NOT a Date Function in SQL?

• DATE()
• NOW()
• THEN()
• DAY()

Answer explanation

THEN() is not a valid SQL date function. DATE(), NOW(), and DAY() are used to manipulate or retrieve date-related information.

What will be the output of the following SQL function? SELECT MOD(53, 10);

• 5
• 3
• 10

Answer explanation

MOD(53, 10) returns the remainder of 53 divided by 10, which is 3.

Which of the following is a characteristic of a relational database?

• Hierarchical structure
• Key-value pairs
• Tabular structure
• Document-based storage

Answer explanation

Relational databases store data in tables with rows and columns, making tabular structure their key characteristic.

What is the purpose of the SQL PRIMARY KEY constraint?

• Allow null values
• Ensure uniqueness
• Link tables
• Check conditions

Answer explanation

PRIMARY KEY ensures that each value in the column is unique and not null.

What does the ACID property 'Isolation' ensure in a transaction?

• Data is permanently saved
• Transactions are processed independently
• Data remains consistent
• All operations are completed

Answer explanation

Isolation ensures that transactions are executed independently of one another.

Which normal form eliminates partial dependencies?

• 1NF
• 2NF
• 3NF
• BCNF

Answer explanation

Second Normal Form (2NF) eliminates partial dependencies by ensuring non-key attributes depend on the entire primary key.

What is the output of SELECT COUNT(*) FROM Table WHERE column IS NULL?

• Number of rows
• Number of non-null values
• Number of null values

Answer explanation

COUNT(*) counts all rows where the condition (column IS NULL) is true, giving the number of null values.

Which SQL command is used to delete a table’s structure and data?

• DELETE
• TRUNCATE
• DROP
• REMOVE

Answer explanation

DROP removes both the table structure and its data permanently.

What is a foreign key in a relational database?

• A unique identifier
• A key linking tables
• A non-unique column
• A temporary key

Answer explanation

A foreign key is a column that creates a relationship between two tables by referencing the primary key of another table.

Which of the following is NOT a type of SQL JOIN?

• INNER JOIN
• LEFT JOIN
• CROSS JOIN
• SIDE JOIN

Answer explanation

SIDE JOIN is not a valid SQL join type. The others are standard join operations.