SQL - return "newest" row from joined files

a order database has two tables, Active orders and Closed orders...
however the closed orders will have the same order number multiple times (order number wraps about 2 times a year).

I have a list of order numbers, and need to return only the "newest"
order data, from either the Active file, or Closed file...

I made the following SQL, and it gets me data for the instance where
the order is no longer active:

select TTTUBID, TTSORD, COALESCE(SORD,OSORD),COALESCE(SPROD,OSPROD)
from datalib.tubtrkpf
left join datalib.activeord on SORD = TTSORD
left join datalib.closedord on OSORD = TTSORD
ORDER BY OTDTE


I think I need a different type of JOIN on my closedord file (inner and outer didn't work)