Top Dense_Rank row based on other fields - sql

Question

I have several tables tied together in sql that I am trying to display only the MAX number from a column formulated using DENSE RANK but I need to keep in mind 2 other fields when pulling the TOP row.
Here is a sample of my result:
| sa_id | price | threshold | role_id | rk
1 | 37E41 | 40.00 | NULL | A38D67A | 1
2 | 37E41 | 40.00 | NULL | 46B9D4E | 1
3 | 1CFC1 | 40.00 | NULL | 58C1E03 | 1
4 | BF0D3 | 40.00 | NULL | 28D465B | 1
5 | F914B | 40.00 | NULL | 2920EBD | 1
6 | F3CA1 | 40.00 | NULL | D5E7584 | 1
7 | 0D8C1 | 40.00 | NULL | EECDB5A | 1
8 | A6503 | 40.00 | NULL | B680CB4 | 1
9 | 9BB96 | 40.00 | 0.01 | D66E612 | 1
10 | 9BB96 | 40.00 | 20.03 | D66E612 | 2
11 | 9BB96 | 40.00 | 40.03 | D66E612 | 3
12 | 9BB96 | 40.00 | 60.03 | D66E612 | 4
13 | 9BB96 | 40.00 | 80.03 | D66E612 | 5
What I am hoping to accomplish is to display all columns in this screenshot using the highest value for rk (calculated using DENSE RANK) where price > threshold and the sa_id & role_id are unique.
In this case I would want to display the following rows only: 1, 2, 3, 4, 5, 6, 7, 8, 10
Is this possible?
SELECT
servicerate_audit_id as sa_id
,ticket_price as price
,threshold_threshold/100.00 as threshold
,charge_role.chargerole_id as role_id
,DENSE_RANK() OVER(
PARTITION BY threshold_audit_id
ORDER BY
ISNULL(threshold_threshold,9999999),
threshold_threshold
) as rk
FROM sts_service_charge_rate
INNER JOIN ts_threshold
ON threshold_id = servicerate_threshold_id
INNER JOIN ts_charge_role as charge_role
ON chargerole_id = servicerate_charge_role_id

Answer 1

If you can modify your original query:
SELECT *
FROM (
SELECT
servicerate_audit_id as sa_id
,ticket_price as price
,threshold_threshold/100.00 as threshold
,charge_role.chargerole_id as role_id
,DENSE_RANK() OVER(
PARTITION BY threshold_audit_id
ORDER BY
ISNULL(threshold_threshold,9999999),
threshold_threshold
) as rk
,DENSE_RANK() OVER(
ORDER BY
ISNULL(threshold_threshold,9999999) DESC,
threshold_threshold DESC
) as rk_inverse
FROM sts_service_charge_rate
INNER JOIN ts_threshold
ON threshold_id = servicerate_threshold_id
INNER JOIN ts_charge_role as charge_role
ON chargerole_id = servicerate_charge_role_id
) t
WHERE price > COALESCE(threshold, 0)
AND t.rk_inverse = 1
Observe I just added an inverse calculation of your ranking and filtered for the top rk_inverse per partition. I'm assuming that the PARTITION BY threshold_audit_id and your requirement of having unique (sa_id, role_id) tuples are functionally dependent. Otherwise, your rk_inverse calculation would need to take into consideration a different PARTITION BY clause.
If you cannot modify your original query:
You can calculate another window function that orders your rk values descendingly (highest first) per your partition (sa_id, role_id), and then take only the top one per partition:
SELECT sa_id, price, threshold, role_id, rk
FROM (
SELECT result.*, row_number() OVER (PARTITION BY sa_id, role_id ORDER BY rk DESC) rn
FROM (... original query ...)
WHERE price > COALESCE(threshold, 0)
) t
WHERE rn = 1