Using aggr function in qlik view

[#1]

Dear Experts ,

My requirement looks simple ,but am i new to qlik view , struggling with below points . please help me .

I am designing new customer report . i want to show list of customer  based on customer booking date .

when the customer should not have any booking for the past 6 months before (from date)  and customer available between my selection date , then we consider it as new customer .

In my example my date selection is from 1st jan 2015 - 30 jan 2015 .

i want to show customer in dimension and booking_date , origin , segment in expression as it is liked below sample output .

in my example i have taken customer A,B,C,D,E,F , below is an sample output  where customer D and F is not an new customer . customer D booking date is not in between of my selection date and customer F booking date is between of selection date but its available with in 6 months before from date .

i have attached qvd , please guide me .

Customer

Booking Date

Segment

Origin

A

20/01/15

04,05

Bangalore , Mumbai

B

30/01/15

4

chennai,delhi

C

20/01/15

2

Ludhiana

E

21/01/15

4

Malayasia

Please suggest .

[#2]

Dear Gysbert ,

Thanks a lot for your help .

Could you please explain me how this expression is working , it will exclude all the customer based on condition ?

=date(aggr(

Max({<

  Booking_date={">=$(vFromDate)<=$(vToDate)"},

  Customer=e({<Booking_date={">=$(=num(addmonths($(vFromDate),-6)))<$(vFromDate)"}>}Customer)

  >} Booking_date)

,Customer),'DD-MMM-YYYY')

[Gysbert_Wassenaar]

Customer=e({<Booking_date={">=$(=num(addmonths($(vFromDate),-6)))<$(vFromDate)"}>}Customer)

The e() function is to selected excluded values. In this case select those customers that do not have a record with a booking date in the six months preceding the vFromDate date.