SQL update from one Table to another based on a ID match

Question

I have a database with account numbers and card numbers. I match these to a file to update any card numbers to the account number, so

Answer 1

In case the tables are in a different databases. (MSSQL)

update database1..Ciudad
set CiudadDistrito=c2.CiudadDistrito

FROM database1..Ciudad c1
 inner join 
  database2..Ciudad c2 on c2.CiudadID=c1.CiudadID