Excel Calculate date difference wherever a date appears

[davidcantor]

I have an excel Pivot with data like this
Type Date1 Date2 DateDiff
1 1/1/20 12/1/19
2 1/2/20
3 1/3/20 10/1/19
4 1/4/20
5 1/5/20 15/12/19
6 1/6/20


I only need the difference (number of days) between date1 and date2 if there is a date on the date2 column

[HansV]

Could you attach a small sample workbook? Thanks in advance.