Question : update from a 3 table join

I have a select statement like:
select columns
from
tableA
join
TableB
join
TableC

I want to update some rows in tableC based on tableA. What is the best syntax to do that?

would
Update tableC C
set
column1=a.column1 ,
column2=a.column2.....

from
tableA
join
TableB
join
TableC

be right and OK? any better way to do it?

thanks

Answer : update from a 3 table join

Windows\System32\Config for:
HKEY_LOCAL_MACHINE\SAM
HKEY_LOCAL_MACHINE\SECURITY
HKEY_LOCAL_MACHINE\SOFTWARE
HKEY_LOCAL_MACHINE\SYSTEM
HKEY_USERS\.DEFAULT

HKEY_LOCAL_USER
is stored in %UserProfile%\AppData\Local\Microsoft\Windows\Usrclass.dat