SELECT CASE WHEN sconto < 20 THEN 0 WHEN sconto >= 20 and sconto <50 THEN 20 WHEN sconto >= 50 and sconto <100 THEN 50 ELSE 100 END AS sconto
SELECT CASE WHEN sconto < 20 THEN 0 WHEN sconto >= 20 and sconto <50 THEN 20 WHEN sconto >= 50 and sconto <100 THEN 50 ELSE 100 END AS sconto