Day 7/7 – SQL Challenge FINALE 🎯 This query was slow on 10M+ rows 👇 Execution time: 8.4s ❌ SELECT * FROM Orders WHERE customer_id IN ( SELECT id FROM Customers WHERE country=‘USA’ ) AND YEAR(order_date)=2024; Optimized version — 2.1s ✅ (4x faster): SELECT o.order_id, o.customer_id, o.amount, o.order_date FROM Orders o JOIN Customers c ON o.customer_id = c.id WHERE c.country=‘USA’ AND o.order_date >= ‘2024-01-01’ AND o.order_date < ‘2025-01-01’; What changed: ✔ Selected only needed columns ✔ JOIN instead of IN ✔ Date range instead of YEAR() ✔ Index-friendly filters Optimization tips: 🔹 Avoid functions on indexed columns 🔹 Use EXPLAIN ANALYZE 🔹 Index filter + join columns 🔹 Avoid SELECT * 🔥 7 Days Complete! Drop “COMPLETED” if you finished the SQL Challenge! #SQLChallenge #Day7 #QueryOptimization #DataScience #SQL FAANG 7DaysComplete SQLMastery