Help finding unique values to count

[mcmcd99]

How do I use the count() function to count the number of unique values in a report? The report is based on a query that is already counting and grouping another set of values so I can't group by through that.

If I have [callsign] values that contain duplicates, I just want to know the total number of unique call signs on the report.

I tried =Count(iif(Not [callsign]=[callsign],*,IsNull)) but that doesn't seem to be doing it.

Maybe =Sum( Iif(Not [callsign]=[callsign],1,0) )


???

[orange]

Show readers the SQL of the query that is used for your report.

[mcmcd99]

SELECT DISTINCT qry_all.tsdate, qry_all.type, qry_all.callsign, Count(qry_all.callsign) AS CountOfcallsign, qry_all.clarity
FROM qry_all
GROUP BY qry_all.tsdate, qry_all.type, qry_all.callsign, qry_all.clarity
ORDER BY qry_all.tsdate;

[mcmcd99]

I'm using it to count the unique call signs of planes that arrive at an airport, and how many transmissions each call sign has, and now I need to count how many of those are clear vs unclear transmissions. I've been trying to do things piece by piece because it's hard to wrap my head around the whole project. I haven't done programming or computer sciency things since college.

[orange]

Can you post a copy of your database? (zip format).