count a column but duplicates once if the column date is greater then a specific date

[zamani_mustafa91]

I want to count number of product which are older then a specific date
count them all but duplicates once

 

[SanjayGMusafir]

I want to count number of product which are older then a specific date
count them all but duplicates once

Use UNIQUE function to find Unique items

Put that in FILTER function to get Unique values after or before a particular date.