Using INTERVAL function with IF condition

[aghabdurauf]

I have three dates: Supreme Case date, Appeal Case date, and Primary Case date. I want to create a logic that processes these dates as follows:

1. If the Supreme Case date is available, skip the other dates and calculate the interval days by subtracting the Case Filing date from the Supreme Case date.
2. If the Supreme Case date is not available but the Appeal Case date is, skip the Primary Case date and calculate the interval days by subtracting the Case Filing date from the Appeal Case date.
3. If only the Primary Case date is available, calculate the interval days by subtracting the Case Filing date from the Primary Case date.

I implement this logic

if(Len(Trim([Supreme case No])) = 1
and Len(Trim([Appeal No])) = 1 or Len(Trim([Appeal No])) = 0
and Len(Trim(Primary_Decree_No)) = 1 or Len(Trim(Primary_Decree_No)) = 0,
Num(Interval(Supreme_Court_Date - Filling_Date,'DD')),Num(Interval(Supreme_Court_Date - Filling_Date,'DD')))

[marcus_sommer]

It could be simplified with alt() which returned the first numerical value. This may look like:

interval(alt(Date1, Date2, Date3) - Date4)