Note: fields want | fields - ignore is redundant. Because if you narrow the field list to just the want field, then there is no ignore field to remove.
Also, when you're using subsearches it can be helpful to look at the search inspector "Actions > Inspect Search". You'll see that just putting NOT in front of a subsearch will not NOT the entire subsearch set. I think it will only NOT the first parenthetical term. Possibly wrapping the entire subsearch in parens will do it. Otherwise you'll have to play around with the format command if you want to take this approach.
A subsearch might be the way to go. However for fun here's an approach that doesn't use subsearches. This shows URL's in access data that were accessed previously in the time range, but not accessed today.
sourcetype=access_combined | eval happened_today=if(relative_time(now(),"@d")<=_time,1,0) | eval happened_before=if(relative_time(now(),"@d")>_time,1,0) | streamstats sum(happened_today) as happened_today sum(happened_before) as happened_before by url | stats count by url happened_today happened_before | search happened_before>0 happened_today=0
