SQL query using WHERE IN clause

Question

This might be simple but I\'m new to SQL and couldn\'t find how to do this exactly.

and I have following table:

Answer 1

I Postgres, I think distinct on does what you want:

select distinct on (dim, frequency) s.*
from sample_tbl s
order by dim, frequency, date desc, version desc;

For each dim/frequency combination this returns one row. That row is the first row encountered based on the order by clause.