SQL Query Validate Records Multiple Tables - Help Needed

Hello...

I am trying to validate a asset number (10 Characters) from one table
to another table. Problem is they are in two different DB's and
haven't done that before?

Basically trying to take record 1 from Table 1/DB1 and validate it
against record 1 in Table 2/DB2 if the record doesn't exist in Table 2/
DB2 update the flag to N  in Table 1/DB1..... Seems easy but been
working on it for about a week now no luck.... :-( I have the mostly
the same colums in both tables but Table 2/DB2  is the host table I
need to verify from....

Does anyone have any help or code to help me do this??

Thanks