**Performance Tips:**

- IS NULL can use indexes (but slower than equality)

- Consider using default values instead of NULL

- NULL-safe comparisons: Use COALESCE in WHERE

- Avoid NULL in frequently filtered columns

IS NULL can use indexes (but slower than equality)

Consider default values instead of NULL

NULL-safe comparisons with COALESCE

Avoid NULL in frequently filtered columns

Using = NULL instead of IS NULL

NULL in calculations returns NULL (propagates)

Concatenation with NULL returns NULL

Forgetting to handle NULL in business logic

Assuming NULL = 0 or NULL = empty string