Clarity

Anyone have any experience or expertise using the DateDiff Function and how to exclude non-workdays (Saturday & Sunday)

I am using the below function, but that only works if it is always divisible by 7 and assuming the start date begins on a Sunday and ends on a Saturday.

((DateDiff(start_date,end_date,""))-((DateDiff(start_date,end_date,"")/7)*2)+1)

My suggestion:

select inv.code, inv.schedule_start, inv.schedule_finish,
(SELECT COUNT(*) FROM DUAL WHERE TO_CHAR(trunc(inv.schedule_start) + LEVEL - 1, 'DY') NOT IN ('SAT', 'SUN') CONNECT BY LEVEL <= trunc(inv.schedule_finish) - trunc(inv.schedule_start) + 1   )  Weekday_Count
  from inv_investments inv

Above is for Oracle.