'CustomerData': A table of DATES and CUSTOMERS, each register show the date when a customer made a purchase. Fields Date, Customer.
'Date_Star' : A table with all the dates from CustomerData.Date. Only a field called DateStar
'Date_End' : A table with all the dates from CustomerData.Date. Only a field called DateEnd.
The user can select a 'DateStar' an a 'DateEnd'. Obviously DateStar <= DateEnd.
QlikView must select those registers that the Date is between DateStar and DateEnd, and search if for each customer exist other register at least 30 days. QlikView count how many customers match.
Example:
DateStar 04/02/2013 (Feb 04, 2013)
DateEnd 14/02/2013 (Feb 14, 2013)
Then, this registers are between the dates given:
Date Customer
04/02/2013 2190038
11/02/2013 2190034
14/02/2013 2190031
And checking the data:
Customer 2190038: previous purshase 06/01/2013. Then 04/02/2013 - 06/01/2013 = 29 days. <-- (Less than 30)
Customer 2190034: previous purshase 30/10/2012. Then 11/02/2013 - 30/10/2012 = 104 days. <-- (Greater than 30)
Customer 2190031: previous purshase 14/01/2013. Then 14/02/2013 - 14/01/2013 = 31 days. <-- (Greater than 30)
