A bit late, but as I arrived here, maybe it's usefull for another one.   You are missing one more final "where" clause, that ensures that if there is no correlation between tables, it leaves the actual value, and not an empty value.   update    work.INVENTORY_COPY as u     set ACTUAL_FUNDING_DT= (         select ACTUAL_FUNDING_DT         from WORK.CONFIG_BACKFILL as n         where u.SIMPLE_ID=n.SIMPLE_ID     ) where u.SIMPLE_ID in (select SIMPLE_ID from WORK.CONFIG_BACKFILL);   More details here: http://support.sas.com/documentation/cdl/en/sqlproc/63043/HTML/default/viewer.htm#p0z9p6hclwnhxin1mrewxhdz5f26.htm ... View more