How to update column in another database

I want to update the values in a column in a table in another database based on the values in a column in a table in a local database. Is this possible? I wanted to use a command like:

UPDATE table1_at_db1 a, table2 b
  SET a.column1 = b.column2
  WHERE a.col_id = b.col_id

That didn't seem to work and I don't know whether I'm just using the wrong syntax or whether what I want to do just isn't possible.

Please advise.

Thanks,

Ron

-- 
Ron McBay                               |
usul_at_auctr.edu                          |
Asst Dir Administrative Data Processing |
Atlanta University Center, Inc.         |