CREATE TABLE #Hours (FixHours INT, AddHours INT, CalCulatedValue INT)
INSERT INTO #Hours VALUES (10,0,14),(5,0,14),(5,1,16),(0,5,17)
SELECT * FROM #Hours h
SELECT FixHours, AddHours, CalCulatedValue FROM #Hours h
WHERE NOT (h.FixHours > 0 AND h.AddHours > 0)
UNION ALL
SELECT FixHours, 0, h.CalCulatedValue FROM #Hours h
WHERE h.FixHours > 0 AND h.AddHours > 0
UNION ALL
SELECT 0, AddHours, h.CalCulatedValue FROM #Hours h
WHERE h.FixHours > 0 AND h.AddHours > 0