Trying to figure out oldest vaccine and most recent vaccine - need help coding

[HyunJee]

I have a dataset which contains vaccination data for several patients.

Each patient can have the same shot multiple times over several years. What I want to know is, is what is the earliest shot they ever had and was is the most recent, regardless of type of shot. Not sure how to do this or where to start.

I am very familiar with SAS, but it has been a long time since I have had to do such data manipulation and data pulling. Any help

you can provide is much appreciated. Thank you !

Best,

HyunJee

[DLing · Accepted solution]

proc sort data=have;

     by patient date vaccine;

run;

data want;

     set have;

     by patient date;

     if first.date then do;

          type = 'earliest';   output;

     end;

     if last.date then do;               *--- could be the same as earliest;

          type = 'latest';   output;

     end;

run;

Once infected by SAS, there is no cure.