heighest salary in any position...

SELECT netAmt FROM jppPurchaseOrder AS P
WHERE 1 = (SELECT COUNT(*) FROM jppPurchaseOrder WHERE netAmt>p.netAmt)

FOR '0' its Top1
FOR '1' its Top2
FOR '2' its Top3

etc...

for 2nd heighest

SELECT Max(netAmt) FROM jppPurchaseOrder
WHERE netAmt < (SELECT Max(netAmt) FROM jppPurchaseOrder)