I have the following query which works for me:
select count(*) from ( select UNIQUE col1, col2, col3 from my_table where cond1 = 'A' and cond2 = 'B' and cond3 = 'C' )
Is it possible to write this without the nested query?
Not that I recommend it, but:
A nested query seems like "the right answer" to me.