SQL - Structured Query Language Data Manipulation Language (DML) Questions and Answers

Question 1

Which of the following SQL statements is NOT considered a Data Manipulation Language (DML) command?

Accepted Answer

CREATE

Answer

UPDATE

Answer

INSERT

Answer

DELETE

Question 2

A database administrator needs to remove all rows from a large 'Log_Archive' table quickly, without the need to roll back the operation. Which SQL command is the most efficient for this task?

Accepted Answer

TRUNCATE TABLE Log_Archive;

Answer

DELETE FROM Log_Archive;

Answer

DROP TABLE Log_Archive;

Answer

UPDATE Log_Archive SET IsActive = 0;

Question 3

A developer needs to synchronize a 'Products' table with a 'Staging_Products' table. The operation should insert new products, update existing products with new prices, and delete products that no longer exist in the staging table, all within a single atomic statement. Which DML command is best suited for this scenario?

Accepted Answer

MERGE

Answer

UPDATE

Answer

INSERT

Answer

A series of INSERT, UPDATE, and DELETE statements

Question 4

What is the primary purpose of the `INSERT INTO ... SELECT` statement in SQL?

Accepted Answer

To copy rows from one existing table and add them to another existing table.

Answer

To update existing records in one table based on values from another table.

Answer

To create a new table and populate it with data from an existing table.

Answer

To insert a single, manually specified row into a table.

Question 5

You are tasked with increasing the salary of all employees in the 'Sales' department by 5%. Which DML query correctly performs this action?

Accepted Answer

UPDATE Employees SET Salary = Salary * 1.05 WHERE Department = 'Sales';

Answer

INSERT INTO Employees (Salary) VALUES (Salary * 1.05) WHERE Department = 'Sales';

Answer

ALTER TABLE Employees SET Salary = Salary * 1.05 WHERE Department = 'Sales';

Answer

SELECT Salary * 1.05 FROM Employees WHERE Department = 'Sales';

Question 6

When using the `DELETE` statement with a `WHERE` clause, what is the effect on the table?

Accepted Answer

It removes only the rows that satisfy the condition specified in the WHERE clause.

Answer

It removes all rows from the table, but the table structure remains.

Answer

It deactivates the specified rows, but they physically remain in the table.

Answer

It removes the entire table, including its structure and data.