Query to retun the sum total of values

Question

My PO table structure is
PO_no PO_VER_ID PO_TOTL_AMT
1111 1     2000
2222 1 1000
1111 2 100
How do I write a query that will have return me sum(PO_TOTL_AMT) of the PO_NO with max(PO_VER_ID). My Result should be
SUM(PO_TOTL_AMT) = 1100. i.e sum of PO_NO 2222 with PO_VER_ID = 1 and PO_NO 1111 with version 2
Can it be performed by a single SQL query.
Thanks in advance
Regards

Answer 1

WITH t AS (SELECT 1111 po_no, 1 po_ver_id, 2000 po_totl_amt FROM dual
UNION
SELECT 2222, 1, 1000 FROM dual
UNION
SELECT 1111, 2, 100 FROM dual)
SELECT SUM(po_totl_amt)
FROM (SELECT po_totl_amt
, RANK() OVER (PARTITION BY po_no ORDER BY po_ver_id DESC) rnk
FROM t)
WHERE rnk = 1;