Help needed on recursive sql - response (1) by dnoeth

I can't match your sample data and required output based on your narrative.
But it seems you don't need recursion, a simple OLAP function might be enough:

SELECT
   SUM(tot_cost + tot_retail + tot_units) 
   OVER (ORDER BY weekdayofyr
         ROWS BETWEEN 1 PRECEDING AND  1 PRECEDING),
   SUM(cost) AS tot_cost,
   SUM(retail) AS tot_retail, 
   SUM(units) AS tot_units,
   weekdayofyr
FROM tab
GROUP BY weekdayofyr
ORDER BY weekdayofyr

Dieter