Flagging duplicates as 1, 2 ...n

[advmsj]

Hi there, I am trying to flag duplicate values in my data set.

I have this:

ID	BirthDate
1	12/07/95
1	12/07/95
1	12/07/95
2	12/24/99
2	12/24/99
3	07/26/98
4	09/29/82

and I want this:

ID	BirthDate	Recurrent
1	12/07/95	1
1	12/07/95	2
1	12/07/95	3
2	12/24/99	1
2	12/24/99	2
3	07/26/98	1
4	09/29/82	1

I found the following code in the communities forum but I cannot seem to make it work... Any help is appreciated.

data want;
count=0;
do until (last.BirthDate);
set have;
by ID BirthDate;
if first.BirthDate then count + 1;
end;
if count > 1 then Recurrent=1; else Recurrent=0;
do until (last.BirthDate);
set temp_names;
by ID BirthDate;
output;
end;

run;

[novinosrin · Accepted solution]

data have;
input (ID	BirthDate) (:$15.);
cards;
1	12/7/1995
1	12/7/1995
1	12/7/1995
2	12/24/1999
2	12/24/1999
3	7/26/1998
4	9/29/1982
;

data want;
 set have;
 by id birthdate;
 if first.BirthDate then Recurrent=1;
 else Recurrent+1;
run;

ID	BirthDate	Recurrent
1	12/7/1995	1
1	12/7/1995	2
1	12/7/1995	3
2	12/24/1999	1
2	12/24/1999	2
3	7/26/1998	1
4	9/29/1982	1

[advmsj]

Thank you so much. I did not realize it was this simple!