SQL Server MERGE with conditions not merging - sql-server

Question

I'm trying to do a simple update of my table when the collector has different data than the final table. I'm using the code below. When the first SELECT runs it tells me that the two columns both have data in them. After the MERGE statement runs, and I do the new SELECT, both of the columns are still showing as NULL. The merge isn't updating anything.
Have I messed up the MERGE syntax somehow?
The production code I have also includes WHEN NOT MATCHED and other items. This is just a small example to demonstrate the problem.
SELECT l.Region_Name, l.Region_Code
FROM dbo.Collector_Locations l
WHERE l.id = 1038
MERGE INTO dbo.Locations AS T
USING dbo.Collector_Locations S ON T.id = S.id
WHEN MATCHED AND (T.Region_Name <> S.Region_Name OR T.Region_Code <> S.Region_Code)
THEN
UPDATE SET T.Region_Name = S.Region_Name,
T.Region_Code = S.Region_Code;
SELECT l.Region_Name, l.Region_Code
FROM dbo.Locations l
WHERE l.id = 1038

Answer 1

Changing the query to accomodate NULL values:
MERGE dbo.Locations AS T
USING dbo.Collector_Locations S
ON T.id = S.id
WHEN MATCHED AND (ISNULL(T.Region_Name,'a') <> S.Region_Name OR ISNULL(T.Region_Code,'a') <> S.Region_Code) THEN UPDATE SET
T.Region_Name = S.Region_Name,
T.Region_Code = S.Region_Code;
Apart from that, the syntax looks fine. This should do the trick.
EDIT:
I would however go for a UPDATE statement in this scenario:
UPDATE dbo.Locations
SET T.Region_Name = S.Region_Name,T.Region_Code = S.Region_Code
FROM dbo.Locations T
INNER JOIN dbo.Collector_Locations S
ON T.id = S.id AND (T.Region_Name <> S.Region_Name OR T.Region_Code <> S.Region_Code)
You could also take our the last set of join condition, since the expected end result is going to be the same:
UPDATE dbo.Locations
SET T.Region_Name = S.Region_Name,T.Region_Code = S.Region_Code
FROM dbo.Locations T
INNER JOIN dbo.Collector_Locations S
ON T.id = S.id