Have you worked with writing complex and large SQL queries?

Yes, I have experience working with writing complex and large SQL queries. This includes:

• Using multiple JOINs to combine data from different tables.
• Applying subqueries and nested SELECTs.
• Using aggregate functions (SUM, COUNT, AVG) with GROUP BY.
• Optimizing queries with indexes and proper WHERE conditions.
• Working with window functions for analytics.

Example of a complex query:

SELECT c.customer_id, c.name, SUM(o.amount) AS total_spent
FROM customers c
JOIN orders o ON c.customer_id = o.customer_id
WHERE o.order_date BETWEEN '2023-01-01' AND '2023-12-31'
GROUP BY c.customer_id, c.name
HAVING SUM(o.amount) > 1000
ORDER BY total_spent DESC;

This query allows retrieving a list of customers who spent more than 1000 in a year, sorted by the total amount spent.