Microsoft Jet

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Definition of Microsoft JET (Joint Engine Technology) in Network Encyclopedia.

What is Microsoft Jet?

Jet is a Microsoft database engine technology developed in 1992 and included in a variety of Microsoft products, including Microsoft Access and Microsoft Visual Basic. Jet is not available as a separate product.

Microsoft Jet Database Engine
Microsoft Jet Database Engine

Microsoft Jet, which stands for Joint Engine Technology, is an advanced 32-bit multithreaded database engine that uses transaction logs to track and maintain information and provide fault tolerance. The Jet database engine has its own processors for performing client-based processing of queries and for generating result sets. Jet databases can be accessed using Data Access Objects (DAO) and open database connectivity (ODBC). DAO provides the Component Object Model (COM) interface for accessing indexed sequential access method (ISAM) databases such as Microsoft FoxPro, dBASE, or Paradox through Jet. Native Jet database files usually have the extension .mdb. Jet is used by the directory and information store database services of Microsoft Exchange Server.


Microsoft Jet allows multiple users to access the database concurrently. To prevent that data from being corrupted or invalidated when multiple users try to edit the same record or page of the database, Jet employs a locking policy. Any single user can modify only those database records (that is, items in the database) to which the user has applied a lock, which gives exclusive access to the record until the lock is released. In Jet versions before version 4, a page locking model is used, and in Jet 4, a record locking model is employed.

Typical Connection String

A typical connection string for this provider is:

"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=databaseName;User ID=MyUserID;Password=MyPassword;"


Jet databases are best accessed through DAO (rather than ODBC) because they expose only a limited amount of functionality to ODBC drivers. Jet cannot use ODBC to build queries that use server-side cursors, and it has limited capability for stored procedures and multiple result sets.