Data access objects

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Data Access Objects , in the German-language documentation " Data Access Objects ", usually referred to with the abbreviation "DAO", is an interface library from Microsoft for accessing data and database structures, especially Microsoft Access databases ( MDBs ).

Up to and including Access 97, the DAO library was the standard library for programming access to database objects and data in Access itself. With Access 2000, Access 2002 (Office XP) and Access 2003, DAO was only included for reasons of compatibility (in the Version 3.6), ADO was intended as the standard library . However, DAO is still very popular with Access developers. a. since it allows more specific access to parts of Access than ADO.

In Access 2007, the DAO library under the new long name "Access Database Engine Object Library" with version number 12.0 (file name: ACEDAO.DLL, qualifier in the code continues to be: DAO) is again the standard library for accessing database objects and data in MDBs.

The DAO library offers a two-part object hierarchy: Starting from the base object “DBEngine” there are “Workspace” objects of the types “Jet Workspace” (for access to MDBs) and “ODBCDirect Workspace” (since DAO 3.5, for access to ODBC Data sources) each with different subordinate objects.

A “Jet Workspace” contains “Database” objects that represent MDBs. The data structure of the MDB can be accessed via "TableDef", "Relations" and "QueryDef" objects, the data via " Recordset " objects. There are also “User”, “Group”, “Container” and “Document” objects for access to the Access rights system. In version 12.0, the latter objects (or their properties and methods that specifically relate to the rights system) are completely hidden. A "Jet Workspace" uses the libraries of the Jet engine for actual execution.

An "ODBCDirect Workspace" contains "Connection" objects as an alternative to "Database" objects, but only Recordset objects and, in the case of Connection objects, QueryDef objects. An "ODBCDirect Workspace" accesses the ODBC API via the RDO library . According to the documentation, version 12.0 no longer supports the "ODBCDirect Workspace" and refers to ADO for access to ODBC data sources.

MS Office XP provides a DAO PIA as an interface for .NET with poker world.

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