In my query below, Dealerid A has 2 sponsors: atc and dws. Dealerid B has only 1 sponsor: atc.
I want to get the dealerid B ONLY.
But the query I wrote below return dealerid A and B to me. I could not recall which query code I should use to get the dealerId WHO HAS 'DWS' ONLY
where sponsor <> 'ATC'