dax formula/calculate days since last orders

Question

days since last orders = 
VAR currentCustomers = MAX('stats de vente'[client])
VAR currentDate = 'stats de vente'[date]
VAR lastOrderDate = 
CALCULATE(
    MAX('dim date'[Date]),
    FILTER(
        ALL('stats de vente'),
        'stats de vente'[client] = currentCustomers &&
        'stats de vente'[date] < currentDateDate
    )
)
RETURN IF(lastOrderDate = BLANK(), BLANK(), currentDate - lastOrderDate)

i have this error It is impossible to determine a unique value for the “customer” column in the “sales stats” table. This can occur when a measurement formula refers to a column that contains many values, without specifying an aggregation such as min, max, count, or sum to obtain a single result.

I would like to have the number of days elapsed between two customer orders.

Answer 1

I think the issue here is var currentDate. It needs to have one value, so try:

days since last orders = 
  VAR currentCustomers = MAX('stats de vente'[client])
  VAR currentDate = MAX('stats de vente'[date])
  VAR lastOrderDate = 
    CALCULATE(
      MAX('dim date'[Date]),
      FILTER(
        ALL('stats de vente'),
        'stats de vente'[client] = currentCustomers &&
        'stats de vente'[date] < currentDateDate
      )
  )
  RETURN IF(NOT ISBLANK(lastOrderDate), INT(currentDate - lastOrderDate) )