Hi @hharrington ,
It seems that I found a solution which may work for your case.
Here is an example of such query:
In this query I searched sample_id by condition which includes presense of 2 entries. Pay attention to the having clause - it filters out all sample_id which have less than 2 entries.
In your case, number in having clause should always match number of elements which should be present in your sample.
If you have any further questions post them here and I will try to help.
Regards, Andriy