Access File Formats: ACCDB vs MDB

Access 2007 and 2013 use the ACCDB file format

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Prior to its 2007 release, the Microsoft Access database file format was MDB. Access 2007 and Access 2013 use the ACCDB file format. While later releases continue to support MDB database files for backward compatibility purposes, the ACCDB file format is the recommended choice when working in Access.

ACCDB File Format Benefits

The new format supports functionality that is not available in Access 2003 and earlier.

Specifically, the ACCDB format allows you to:

  • Include attachments in your database. The ACCDB format allows you to store file attachments and other binary large objects (or BLOBs) in database fields. This is a feature long common to enterprise databases such as Oracle and SQL Server that had been missing from Microsoft Access.
  • Use multivalued fields. While database purists may scoff at the idea of multivalued fields because they defy the principles of normalization, they’ll make life easier for developers of simple databases. Multivalued fields allow users to select one or more options for a field value by using check boxes. For example, you could create a single Shirt Sizes field with the values S, M, L, and XL. Users could then select all values that apply from the multivalued field.
  • Safe integration with SharePoint and Outlook. SharePoint and Outlook both block MDB databases due to security concerns. Improvements in the database security model allow for the security validation of database files and both SharePoint and Outlook trust this validation.
  • Encryption improvements. Users of ACCDB files can leverage the Windows Cryptographic API for database encryption. This capability is especially important to avoid identity theft in which an encrypted database can mean the difference between an embarrassing and costly security incident and a non-event. 

    Compatibility of ACCDB With Older Access Versions

    If you have no need to share files with databases created in Access 2003 and earlier, then there is no reason to try to be backward compatible by using an MDB format.

    There are also two limitations that you should consider when using ACCDB. ACCDB databases do not support user-level security or replication. If you need either of these features, you can still use the MDB format.

    Converting Between ACCDB and MDB File Formats

    If you have existing MDB databases created with earlier versions of Access, you can convert them to ACCDB format. Simply open them in any post-2003 version of Access, select the File menu, and then Save As.  Choose the ACCDB format.

    You can also save an ACCDB database as an MDB formatted file if you need to work with Access versions prior to 2007. Just follow the same procedure, but choose MDB as the Save As file format.