MS Access to Oracle easy Conversion / Migration
The Migration Workbench which comes with Oracle's (free) SQL Developer tool supports migrating from MS Access. Find out more.
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Because I don't use MS Access myself I missed an important point: SQL Developer doesn't support migration from Access 2007. However, according to this thread on the OTN SQL Developer forum, it can be made to work with the latest version of SQL Developer (that is, 2.1).