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Beginner About 15 min
NULL Handling
Why NULL breaks comparisons and how to fix it with COALESCE, NULLIF, and IS NULL.
What you'll learn
- Understand why NULL means "unknown" and breaks = comparisons
- Use IS NULL and IS NOT NULL to filter missing data
- Replace NULLs with default values using COALESCE
- Prevent division-by-zero errors with NULLIF
- Chain NULL functions for real-world data cleanup