How to get a percentile rank based on a computation - sql

Question

there are four tables as :
T_SALES has columns like
CUST_KEY,
ITEM_KEY,
SALE_DATE,
SALES_DLR_SALES_QTY,
ORDER_QTY.
T_CUST has columns like
CUST_KEY,
CUST_NUM,
PEER_GRP_ID
T_PEER_GRP has columns like
PEER_GRP_ID,
PEER_GRP_DESC,
PRNT_PEER_GRP_ID
T_PRNT_PEEER has columns like
PRNT_PEER_GRP_ID,
PRNT_PEER_DESC
Now for the above tables, i need to generate a percentile rank of the customer based on the computation fillrate = SALES_QTY / ORDER_QTY * 100 by peer group within a parent peer.
could someone please help on this?

Answer 1

You can use the analytic function PERCENT_RANK() to calculate the percentile rank, as below:
SELECT
t_s.cust_key,
t_c.cust_num,
PERCENT_RANK() OVER (ORDER BY (t_s.SALES_DLR_SALES_QTY / ORDER_QTY) DESC) as pr
FROM t_sales t_s
INNER JOIN t_cust t_c ON t_s.cust_key = t_c.cust_key
ORDER BY pr;
Reference:
PERCENT_RANK on Oracle® Database SQL Reference

Answer 2

If by "percentile rank" you mean "percent rank" (documented here), then the harder part is the joins. I think this is the basic data that you want for the percentile rank:
select t.PEER_GRP_ID, t.PRNT_PEER_GRP_ID,
sum(SALES_DLR_SALES_QTY * ORDER_QTY) as total
from t_sales s join
t_customers c
on s.CUST_KEY = c.cust_key join
t_peer_grp t
on t.PEER_GRP_ID = c.PEER_GRP_ID
group by t.PEER_GRP_ID, t.PRNT_PEER_GRP_ID;
You can then calculate the percentile (0 to 100) as:
select t.PEER_GRP_ID, t.PRNT_PEER_GRP_ID,
sum(SALES_DLR_SALES_QTY * ORDER_QTY) as total,
percentile_rank() over (partition by t.PRNT_PEER_GRP_ID
order by sum(SALES_DLR_SALES_QTY * ORDER_QTY)
)
from t_sales s join
t_customers c
on s.CUST_KEY = c.cust_key join
t_peer_grp t
on t.PEER_GRP_ID = c.PEER_GRP_ID
group by t.PEER_GRP_ID, t.PRNT_PEER_GRP_ID;
Note that this mixes analytic functions with aggregation functions. This can look awkward when you first learn about it.