What level of complexity do your SQL queries have?

The level of complexity of SQL queries I write is usually medium. This means I am confident in working with:

• Complex selections with multiple JOINs, including INNER, LEFT, RIGHT JOIN.
• Using aggregate functions (SUM, COUNT, AVG) and GROUP BY, HAVING.
• Subqueries and correlated subqueries.
• Operations with window functions (ROW_NUMBER, RANK, etc.).
• Query optimization, understanding indexes and execution plans.

For example, I can write a query to get the top 5 clients by order amount in the last month:

SELECT c.customer_id, c.name, SUM(o.amount) AS total_amount
FROM customers c
JOIN orders o ON c.customer_id = o.customer_id
WHERE o.order_date >= DATEADD(month, -1, GETDATE())
GROUP BY c.customer_id, c.name
ORDER BY total_amount DESC
LIMIT 5;

Thus, I can solve tasks of medium complexity that require understanding of the relational model and optimal query construction.