@mkeintz that's why the first line reads "This yields the same result ... if you only have one record for that subjectID"
Since we now know that there are several records, the OP needs to think about how he wants to organise his data.
What are you actually trying to do?
Why would you join every Adverse Event record with every Medical History record? What possible meaning could you get from that?
Did you just want to create separate output tables for each input table instead?
data work.dm;
set seretide.dm ;
where subjectid='0001' ;
run;
data work.ae;
set seretide.ae ;
where subjectid='0001' ;
run;
data work.cm;
set seretide.cm ;
where subjectid='0001' ;
run;
...
Don't miss out on SAS Innovate - Register now for the FREE Livestream!
Can't make it to Vegas? No problem! Watch our general sessions LIVE or on-demand starting April 17th. Hear from SAS execs, best-selling author Adam Grant, Hot Ones host Sean Evans, top tech journalist Kara Swisher, AI expert Cassie Kozyrkov, and the mind-blowing dance crew iLuminate! Plus, get access to over 20 breakout sessions.
Learn how use the CAT functions in SAS to join values from multiple variables into a single value.
Find more tutorials on the SAS Users YouTube channel.