Subqueries in FROM Clause (Derived Tables): Examples

Pre-Aggregated Data

intermediate

Calculate statistics on filtered data

SELECT department, AVG(salary) as avg_salary FROM (SELECT * FROM employees WHERE hire_date > '2023-01-01') AS recent GROUP BY department;

department | avg_salary

Engineering | 85000

Sales | 72000

Subquery filters first, outer query aggregates. More efficient than filtering after aggregation.

All