What happens to the NULL bonus?

Question

Accepted Answer

CASE WHEN bonus IS NULL THEN 0 ELSE bonus END replaces NULL with 0. Alice has a bonus (5000), so the ELSE returns 5000. Bob has NULL, so the WHEN matches and returns 0. This is equivalent to COALESCE(bonus, 0), which is shorter. Use CASE when you need more complex NULL replacement logic (e.g. different defaults by department).