Great idea ... I came up with the data step approach below but I think this works even better! I expanded the sample data to add a few more test cases in it. data trans;   infile cards dlm=',';   input store customer transaction;   cards; 1,               10,                   7171 2,              21,                   8389 3,               40,                   5118 3,               40,                   8971 4,               40,                   9008 4, 30, 10000 5,               88,                   6673 5, 40,3333 6, 33,2222 3, 22,4555 7,22,5555 8,33,1111 9,33,8888 ; run; data storepairs;   infile cards dlm=',';   input store pair $;   cards; 3, P1 4, P1 6, P2 8, P2 ; run; proc sql;   create table transpair as   select a.*, b.pair   from trans as a , storepairs as b   where a.store = b.store   /*group by pair, customer   having count(distinct store)=2*/   order by b.pair, a.customer, a.store   ; quit; data transpair2;   set transpair;   by pair customer store;   if first.customer then do;   match = store;   both = 0;   end;   if match ne store then both = 1;   retain match both;   if both = 1 then output; run; proc sql;   create table final as   select a.*   from transpair as a , transpair2 as b   where a.pair = b.pair and a.customer = b.customer   ; quit; At least the two approaches should be able to give so insight into alternatives. EJ ... View more

The first post just leaves you with the transactions of the pairs and I not completely sure what the rest of the need is. So if more is needed reply back and we can continue the solution. EJ ... View more

Here is how I would approach ... somehow you will have to tell sas the pairs you are interested in either by manual coding the 20 pairs or creating a separate excel and reading it in.  Remember you need to link stores to pairs so have a row per store in you "pair table" seems like a better approach. Here is what I did using your sample data (I just read in the data you had and made a pair table with the stores in the pair and A pair id that you could make into whatever you need): data trans;   infile cards dlm=',';   input store customer transaction;   cards; 1,               10,                   7171 2,              21,                   8389 3,               40,                   5118 3,               40,                   8971 4,               40,                   9008 5,               88,                   6673 ; run; data storepairs;   infile cards dlm=',';   input store pair $;   cards; 3, P1 4, P1 ; run; proc sql;   create table transpair as   select a.*, b.pair   from trans as a , storepairs as b   where a.store = b.store   ; quit; Hope this helps! EJ ... View more

The attached does not currently create a pdf that I could see. It looks like the output from the mixed procs are being outputed to datasets. I would comment out the proc datasets step in the macro and try to assemble the output you want from the datasets. Hope this helps EJ ... View more

Thanks Reeza! I have attended some of Peter workshops in the past ... I will see if the data is still available! EJ ... View more

Fingers faster than brain ... Hash objects is what I am referring too. EJ ... View more