Count the rows returned by a subquery using the SELECT DISTINCT option, e.g.

SELECT COUNT(*) AS SR_Count
FROM (SELECT DISTINCT SR
            FROM YourTable) AS T1;

You'll find Access will change it a bit after you save it, changing the
parentheses to brackets and adding a dot after the subquery.  It will work
just the same though.

Ken Sheridan
Stafford, England