How to bring back rows where no result set is found

Question

1. Here is my problem I am trying to get some counts on ID's that did not match.
2. My expected result set is the replicationTime column (eg 201701, 201702...), when I do my count I only have NULL values for 201702, but not 201701...is there a way to bring back all the existing replicationTime values (ie 201701 AND 201702) but padded the count column with a zero or a NULL? I basically need to bring back two rows, but only one comes back which is the one that had no matches

select replicationTime, count(*) as CountsForNoMatches
from table 
where ID IS NULL
Group By ReplicationTime

3. I have tried using ISNULL... but It is not bringing back anything other than the same row.
4. Also, keep in mind this is the portion of a Subquery and it serves a larger picture in the overall query where I need all rows and not just one otherwise my result set returns nothing.

Answer 1

Like this

select replicationTime, sum(case when ID is null then 1 else 0 end) as CountsForNoMatches
from table 
Group By ReplicationTime

or

select replicationTime, max(case when ID is null then 1 else 0 end) as CountsForNoMatches
from table 
Group By ReplicationTime

if you just want to know if there is some row with a null ID for that ReplicationTime.