Using the .accdb Database File Format

Since its inception, Microsoft Access has used a database engine named Jet (an acronym for Joint Engine Technology). Beginning with Access 2007 the Microsoft Access development team wanted to add significant new features to Access, such as multi-variable and attachment fields. Because the new features were so significant, it wasn't possible to retrofit Jet with the code necessary to support the new features. As a result, Microsoft developed an entirely new database engine, the Access Connectivity Engine (ACE), for Access 2007, 2010, and future versions of Access.

Access 2010 supports several file formats, including the following:

• Access 2007 .accdb format
• Access 2002-2003 .mdb format
• Access 2000 .mdb format
• Access 97 .mdb forma

The Access .accdb format supports several new features, such as multivalued fields and attachments, not available in previous versions (.mdb). The new file format can't be opened or linked to earlier versions of Access (although you can link tables in earlier versions to an .accdb file). The .accdb file format doesn't support replication or user-level security. If you need to use an Access 2010 database with earlier versions of Access or use replication or user-level security, you must use the .mdb file format.

You can open and even run Access 97 database files, but you can't make any design changes in the Access 97 .mdb file. You can open Access 2002-2003 and Access 2000 database files and make any desired changes to them. However, you'll only be able to use features specific to those versions. Some of the new Access features won't be available, particularly those features that rely on the ACE database engine.

The default database file format in Access 2007 and 2010 is .accdb. You can convert a database saved in a previous format by opening the database in Access 2010, clicking the File menu in the upper-left corner of the main Access screen to open the Access Options dialog box, and selecting the Share tab. The Share tab includes a number of options for saving the current database in a number of different Access formats (.accdb, 2002-2003 .mdb, 2000 .mdb, and so on), or saving individual objects, such as forms or reports, in .pdf or .xps formats.

Tip: Change the default Access file format for new files by opening the Access Options dialog box, selecting the General tab and selecting the file format you'd like to use from the Default File Format dropdown list. When you're creating a new database, you can always select a different file format to use. The default selection simply makes it easier to work with a particular format if necessary.

The Access 2007 file format should be used only in an Access environment where all users are using Access 2007 or 2010. In addition to complete compatibility with all Access 2007 and 2010 features, you may experience some performance advantages when using the Access .accdb file format with larger databases. However, you should stay with the Access 2002-2003 file format for compatibility with a mixed environment of Access 2002, 2003, 2007, or 2010 users. In a mixed environment of Access 2000, 2002, 2003, 2007, or 2010 users; stay with the Access 2000 file format. An Access 2003, 2007, or 2010 program can attach to Access 97 data files, but if you're trying to accommodate Access 97 users, you cannot upgrade the Access 97 data files.