Are you able to write complex SQL queries or at what level approximately?

Yes, I can write complex SQL queries. This usually includes:

• Using multiple JOINs to combine tables
• Nested subqueries
• Aggregations with GROUP BY and HAVING
• Window functions for analytics
• Query optimization using indexes and execution plan explanations

Example of a complex SQL query:

SELECT u.id, u.name, COUNT(o.id) AS orders_count
FROM users u
LEFT JOIN orders o ON u.id = o.user_id
WHERE u.status = 'active'
GROUP BY u.id, u.name
HAVING COUNT(o.id) > 5
ORDER BY orders_count DESC;

This query selects active users with more than 5 orders, sorted by the number of orders.