I want to join my CHEESE table with FRESHNESS to get CHEESE and FRESHNESS code for cheeses where max(seq_no) for each cheese id is MOLD.
When using rank(), where do I join to FRESHNESS?
CHEESE FRESHNESS
CHEESE_ID SEQ_NO FRESH_CODE FRESH_CODE FRESH_DESC
================================= ========================
1 1 MOLD MOLD MOLDY CHEESE
1 23 FRSH FRSH EDIBLE
1 34 FRSH
2 2 FRSH
2 18 MOLD
3 3 MOLD
3 5 MOLD
3 7 MOLD
DESIRED RESULT
==========================
CHEESE_ID SEQ_NO FRESH_CODE FRESH_DESC SEQ_RANK
2 18 MOLD MOLDY CHEESE 1
3 7 MOLD MOLDY CHEESE 1
Here's my code I'm using to get the desired sequence numbers.
select
cheese_id,seq_no,fresh_code,seq_rank
from ( select
cheese_id,seq_no, fresh_code,
rank() over (partition by cheese_id
order by seq_no desc) seq_rank
from cheese
where seq_rank = 1
and fresh_code = 'MOLD'
You can either do the join in the subquery
select cheese_id,seq_no,fresh_code,fresh_desc,seq_rank
from ( select cheese_id,
seq_no,
fresh_code,
fresh_desc,
rank() over (partition by cheese_id
order by seq_no desc) seq_rank
from cheese
join freshness using (fresh_code) )
where seq_rank = 1
and fresh_code = 'MOLD'
or you can join to your subquery
select cheese_id,seq_no,fresh_code,fresh_desc,seq_rank
from ( select cheese_id,
seq_no,
fresh_code,
fresh_desc,
rank() over (partition by cheese_id
order by seq_no desc) seq_rank
from cheese ) cheese_outer
join freshness using (fresh_code)
where seq_rank = 1
and fresh_code = 'MOLD'