What can be called simple depends on your preferences and skills.
By programming: data step merge, update or modify (or even SQL) will solve this "simple" update scenario.
If you are more of point-and-click-person, I think unfortunately the only standard component for this kind of of operation is Query Builder.
There you can do a full outer join. Remember that you need to define calculated columns using coalesce() function.
Ok, perhaps, not that very simple...?
Data never sleeps