I like @Shmuel's idea. If you have a last_modified date on your data set, which a lot of DB's have by default within a data warehouse, you could use that. If you don't, you can kind of create your own.
How is your data modified/updated each time is a bit of the key question. Here's an example of how this could work.
*Original data set;
data class1;
set sashelp.class;
last_update_date = '01Jan2017'd;
run;
*Changes;
data class2;
set sashelp.class;
last_update_date = '02Jan2017'd;
if age=13 then age=21;
else if height>65 then height= 100;
else delete;
run;
*sort for updates;
proc sort data=class1; by name;
proc sort data=class2; by name;run;
*update data set;
data class3;
update class1 class2;
by name;
run;
*find max date;
proc sql noprint;
create table changes as
select *
from class3
having last_update_date = max(last_update_date);
quit;
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