Do while loop

[EMC9]

good day I have a data set below that has user_no (there could be multiple user use_no with different dates)

I want to create a loop that adds a maximum date unitl 201802 for eg:

if the last date for user 123 is 201711 I want the loop the add 201712 / 201801 / 201802

the data looks below :  I have not attempted the code :

user_no	month	New_month
123	201505	201505
123	201506	201506
123	201507	201507
123	201508	201508
123	201509	201509
123	201510	201510
123	201511	201511
123	201512	201512
123	201601	201601
123	201602	201602
123	201603	201603
123	201604	201604
123	201605	201605
123	201606	201606
123	201607	201607
123		201608
123		201609
123		201610
123		""
123		""
123		""
123		""
123		"'
123		201802

[Kurt_Bremser · Accepted solution]

Do by-group-processing and add this in the data step:

output;
if last.user
then do while (new_month < '201801');
  new_month = /* next month to be calculated according to the values; with SAS dates, use the intnx() function */;
  output;
end;

[EMC9]

thank you.