MDA files are files that Add functionality to MS Access. MDA may add functionalty such as automated functions and queries to MS Access database files (MDBs). The MDA file will contain editable Visual Basic for Applications (VBA) source code that is used to created the new added functionality.



Microsoft Access is a relational database management system from Microsoft, packaged with Microsoft Office Professional which combines the Jet relational database engine with a graphical interface intended to make it possible for relatively unskilled programmers and non-programmer "power users" to build front ends to databases. For skilled developers and data architects, it can allow for the rapid development of applications.

Access is widely used by small businesses and hobby programmers to create ad hoc customized systems for handling small tasks. Its ease of use and powerful design tools give the non-professional programmer a lot of power for little effort. However, this ease of use can be misleading. This sort of developer is often an office worker with little or no training in application or data design. Because Access makes it possible even for such developers to create usable systems, many are misled into thinking that the tool itself is limited to such applications.

Some professional application developers use Access for rapid application development, especially for the creation of prototypes and standalone applications that serve as tools for on-the-road salesmen. Access does not scale well if data access is via a network, so applications that are used by more than a handful of people tend to rely on a Client-Server based solution such as Oracle, DB2, Microsoft SQL Server, PostgreSQL, MySQL or MaxDB. However, an Access "front end" (the forms, reports, queries and VB code) can be used against a host of database backends, including Access itself, SQL Server, Oracle, and any other ODBC-compliant product. This approach allows the developer to move a matured application's data to a more powerful server without sacrificing the development already in place.

Many developers who use Microsoft Access use the Leszynski Naming Convention, though this is not universal; it is a programming convention, not a DBMS-enforced rule.