Easy Table Based Update Statement???

Hello,

I have 2 ways of updating data I'm using often

1) via a cursor on TABLE1 update fields in TABLE2
2) via an some of variables ...

SELECT @var1=FLD1, @var2=FLD2 FROM TABLE1 WHERE FLD-ID = @inputVAR
UPDATE TABLE2
SET FLDx = @var1, FLDy = @var2
WHERE ...

Now I have a system with 2 databases and I need to update table DB2.TAB
based on data in DB1.TAB. Instead of using 1 of the 2 ways I normally use,
I thought it would be much easier to get the required data immediately from
DB1.TAB in the update-statement of DB2.TAB ... but the way to do that
confuses me. I've checked books online and a lot of newsgrouppostings
giving good information but still I keep getting errors like this ...

The column prefix 'x.ADS' does not match with a table name or alias name
used in the query.

while executing the following statement ...

UPDATE DB2.dbo.TAB
SET
FLD1 = x.FLD1,
FLD2 = x.FLD2,
...
FROM DB1.dbo.TAB x, DB2.dbo.ADS
WHERE DB2.dbo.TAB.REFID = x.IDOFTAB1 AND DB2.dbo.TAB.IDOFTAB2 =
@InputParameter

So in DB2.TAB I have a field REFID reffering to the keyfield IDOFTAB1 of
table DB1.TAB
AND I only want to update the row in DB2.TAB with the unique keyfield
IDOFTAB2 equal to variable @InputParameter

Do you see what I'm doing wrong?

--
Thank you,
Kind regards,
Perre Van Wilrijk,
Remove capitals to get my real email address,