CASE as a replacement for nested IFs

Question

Accepted Answer

The searched CASE form (CASE WHEN condition THEN result ...) evaluates each WHEN in order and stops at the first TRUE - exactly like an if/elif chain. Because evaluation stops at the first match, WHEN score >= 80 only runs if score < 90 already failed. You do not need WHEN score >= 80 AND score < 90. The simple CASE form (CASE score WHEN 90 THEN ...) only checks equality, not ranges - it would not work here.