There are plenty of ways to achieve this. However, the one that seems most intuitive to me is the following: *Create a master list; data Master; set Table;   if missing(MSA) then delete; run; *Make sure Master has just one entry for each CBSA; proc sort data=Master nodupkey; by CBSA; run; *Create new table as needed; proc sql;   create table Table2 as   select t1.*, t2.MSA as MSA_filled   from Table as t1   left join Master as t2   on t1.CBSA = t2.CBSA ;quit; ... View more

This is always a tricky problem, specially when it gets thrown for something that you were running successfully until recently. And there doesn't seem to be any simple one-step solution for it. Most searches online ended up in dead-ends for me.  So are few solutions which did or did not work for me: 1) a single or double quote used in a comment inside the Macro  - even though its inside a comment, it somehow manages to trigger this warning 2) adding extra space before & after, each instance of single/double quote - this never helped (though it did make me search and understand the difference between using single vs double quote) 3) Using 'PUTN' function - this one was most recent. So maybe there are others functions too, which throw this warning!! My suggestion would be, try commenting your code piece-by-piece and then running it after restarting SAS). Or in case you made any recent changes, start with them first. ... View more