SQL Server Subqueries - Practical Examples Tutorial

Write a Scalar Subquery

Write a query to list employees with their department name using a scalar subquery.

Expected output: A list of employees with their corresponding department names.

Hint: Use a subquery in the SELECT clause to get the department name from the Departments table.

Correlated Subquery Filtering

Write a query to find customers who have placed orders in the last month using a correlated subquery.

Expected output: List of customers with recent orders.

Hint: Use EXISTS with a subquery filtering orders by date.

A correlated subquery is a subquery that references columns from the outer query and executes once per row processed by the outer query.

Use subqueries when you need to filter or calculate values that depend on aggregated or conditional data, or when the logic is simpler with a nested query.

Yes, subqueries can be used in INSERT statements to insert data based on the results of another query.