Select rows by group

[khalidamin]

Want to select patients who had ONLY surgery as ONLY treatment.

[PeterClemmensen]

Patient A has other treatments? Why is he in there?

[PeterClemmensen · Accepted solution]

If I understand you correctly, this is what you want

data have;
input Pt $ malignancy Treatment $;
datalines;
A 1 Chemo
A 1 Surgery
A 1 Radio
A 2 Surgery
B 1 Surgery
C 1 Surgery
C 1 Chemo
D 1 Surgery
;

proc sql;
   create table want as
   select * from have 
   group by Pt, malignancy
   having sum(Treatment='Surgery')=n(Treatment);
quit;

Result:

Pt  malignancy  Treatment 
A   2           Surgery 
B   1           Surgery 
D   1           Surgery 

[khalidamin]

Thank you so much! The solution worked perfectly, appreciate your help.

Pt A was there because that patient had only surgery for malignancy # 2. But, we can't select that patient for malignancy #1 because the patient had multiple treatments for malignancy 1..