Finding the same customer who made duplicate transaction in 12 months

[#1]

Hi All,

I like to seek your kind assistance on the question below.

I would like to find who are the distinct customer who made 2 or more transaction within 12 months. I have created a sample table  and the right answer should be highlighting:

1) Customer A (as there are 2 transactions within 8 months)

2) Customer D (as there are 2 transactions within 11 months)

Can someone advise me pls.

Customer	Transaction Date (MM/YYYY)
A	Apr-14
B	Apr-14
C	May-14
D	Jun-14
A	Dec-15
B	May-15
C	Jun-15
D	May-15

[Gysbert_Wassenaar]

Well, no. The results of chart expressions will not be visible in the script.