Last Recent Record with Value from other column

drop table #abc

CREATE TABLE #ABC
(
CompnayID INT,
TrainingCompanyID INT,
CategoryID INT,
ItemID INT,
LastTrainedBy VARCHAR(40),
LastTrainedOn DATETIME
)


INSERT INTO #ABC VALUES (1, 1, 4, 2, NULL, '2013-06-18 18:06:06.737')

INSERT INTO #ABC VALUES (1, 1, 4, 1, 'Test Acc', '2013-06-18 18:05:22.720')



INSERT INTO #ABC VALUES (1, 1, 5, 2, 'Test Acc', '2013-06-18 18:06:06.737')

INSERT INTO #ABC VALUES (1, 1, 5, 1, nULL, '2013-06-18 18:05:22.720')



SELECT 
	ROW_NUMBER() OVER (PARTITION BY TrainingCompanyID, CompnayID, CategoryID ORDER BY LastTrainedOn DESC) RN,
	CompnayID,
	TrainingCompanyID,
	ItemID,
	CategoryID,
	LastTrainedBy,
	LastTrainedOn
from #ABC


--Required Output
-- Per Category, if there is value of LastTraiedBy then LastTrainedBy with recent LastTrainedOn date, if no value of LastTrainedBy Per Category,  then recent LastTrainedOn

--2	1	1	1	4	Test Acc	2013-06-18 18:05:22.720
--1	1	1	2	5	Test Acc	2013-06-18 18:06:06.737

Thanks, Cool Mind -- If you find my answer helpful, please mark it as Answer.