Data Access with

Overview of Microsoft Database Access Technologies

  • Microsoft has introduced many data base access technologies like ODBC, OLEDB, RDO, DAO (Data Access Object), ADO (ActiveX Data Object)
  • The overall goal is to provide a consistent set of programming interfaces that can be used by a variety of clients to talk to a variety of data sources, including both relational and non relational
  • This is the first mechanism provided by Microsoft to work with databases
  • This provides a C interface to relational databases
  • Using this architecture, applications can talk to different relational databases using the same C interfaces
  • This is widely adopted, and all major relational databases have provided ODBC drivers
  • Some ODBC drivers have been written for non-relational data source, such as Excel spreadsheets
The ODBC architecture
  • There were two main drawbacks to this approach
  • The first one is the restrictions to relational databases.
  • Although drivers are written for RDBMS this approach puts a great burden on the driver to in effect emulate a relational database engine and this code would have to be replicated in each such drive
  • The second drawback is the C interface, which requires a programmer in any other language to first interface to C before being able to call ODBC
  • In this mechanism, the strategy is based on the Component Object Model (COM) which provides a language independent interface, based on a binary standard.
  • Thus, any solution based on COM improve the flexibility from the standpoint of the client program.
  • Microsoft’s set of COM database interface is referred to as “OLE DB”.
  • The best feature is that OLE DB is not specific to relational databases
  • Any data source that wishes to expose itself to client through OLE DB must implement an OLE DB provider.
  • OLE DB itself provides much of the database functionality.
  • The first OLE DB provider was for ODBC
  • This gave OLE DB consumers access to all data sources supporting ODBC.
  • The gain was a COM interface for clients.

However, this solution imposed an additional layer between the client and the database

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