I bit confused with the IN clause.
Does this mean select all data from Customers and put it INTO CustomersBackup2013 table. The CustomersBackup2013 table is located in a file called Backup.mdb
SELECT *
INTO CustomersBackup2013 IN 'Backup.mdb'
FROM Customers;
I believe in JET this is valid syntax for an external database and is for referencing an external databases as described by the OP.
For reference: http://en.wikibooks.org/wiki/JET_Database/Insert