Finding Missing Records with LEFT JOIN IS NULL 🔍 When you need to find rows without a match, LEFT JOIN combined with IS NULL is the correct pattern. A common mistake is checking nullable columns without understanding how joins work. The safest approach is to check a non-nullable key from the right table. 💡 Why this matters • Prevents misleading results • Makes intent clear • Works reliably in analytics and reporting This pattern is widely used for: • Inactive customers • Churn analysis • Data