Try this
SELECT 100+ Sum(CASE WHEN b.name = 'a' THEN b.qty ELSE 0 END)OVER(ORDER BY itemorder DESC) as modifyed_sum, qty, name, itemorder FROM Yourtable ORDER BY itemorder ASC Another way
SELECT 100 + (SELECT Sum(CASE WHEN b.name = 'a' THEN b.qty ELSE 0 END) FROM yourtable b WHERE a.itemorder <= b.itemorder), qty, name, itemorder FROM yourtable a ORDER BY itemorder ASC