-- Compute cummulative business days in a week excluding weekend days (SAT, SUN)

SELECT
 level  day_of_month,
 TO_CHAR(TRUNC(SYSDATE,'MON')+level-1,'DY') day_of_week,
 TRUNC(SYSDATE,'MON')+level-1  month_date, 
 CASE 
   WHEN TO_CHAR(TRUNC(SYSDATE,'MON')+level-1,'DY') IN ('SAT','SUN') THEN 0
   ELSE 1
 END  week_day_idx,
 SUM(CASE 
      WHEN TO_CHAR(TRUNC(SYSDATE,'MON')+level-1,'DY') IN ('SAT','SUN') THEN 0
      ELSE 1
     END)
  OVER(PARTITION BY level)  business_day
FROM  dual
CONNECT BY level <= TO_CHAR(LAST_DAY(SYSDATE),'dd')
;

-- Zero changed to NULL - business day count will still be the same

SELECT
 level  day_of_month,
 TO_CHAR(TRUNC(SYSDATE,'MON')+level-1,'DY') day_of_week,
 TRUNC(SYSDATE,'MON')+level-1  month_date, 
 CASE 
   WHEN TO_CHAR(TRUNC(SYSDATE,'MON')+level-1,'DY') IN ('SAT','SUN') THEN  NULL
   ELSE 1
 END  week_day_idx,
 SUM(CASE 
      WHEN TO_CHAR(TRUNC(SYSDATE,'MON')+level-1,'DY') IN ('SAT','SUN') THEN  NULL
      ELSE 1
     END)
  OVER(PARTITION BY level)  business_day
FROM  dual
CONNECT BY level <= TO_CHAR(LAST_DAY(SYSDATE),'dd')
;