SQL Server 2008 Native Client Programming
SQL Server Native Client is a stand-alone data access application programming interface (API), used for both OLE DB and ODBC, that was introduced in SQL Server 2005. SQL Server Native Client combines the SQL OLE DB provider and the SQL ODBC driver into one native dynamic-link library (DLL). It also provides new functionality above and beyond that supplied by the Windows Data Access Components (Windows DAC, formerly Microsoft Data Access Components, or MDAC). SQL Server Native Client can be used to create new applications or enhance existing applications that need to take advantage of features introduced in SQL Server 2005, such as multiple active result sets (MARS), user-defined data types (UDT), query notifications, snapshot isolation, and XML data type support.
For a list of the differences between SQL Server Native Client and Windows DAC, plus information about issues to consider before updating a Windows DAC application to SQL Server Native Client, see Updating an Application to SQL Server Native Client from MDAC.
The SQL Server Native Client ODBC driver is always used in conjunction with the ODBC Driver Manager supplied with Windows DAC. The SQL Server Native Client OLE DB provider can be used in conjunction with OLE DB Core Services supplied with Windows DAC, but this is not a requirement; the choice to use Core Services or not depends on the requirements of the individual application (for example, if connection pooling is required).
ActiveX Data Object (ADO) applications may use the SQL Server Native Client OLE DB provider, but it is recommended to use ADO in conjunction with the DataTypeCompatibility connection string keyword (or its corresponding DataSource property). When using the SQL Server Native Client OLE DB provider, ADO applications may exploit those new features introduced in SQL Server 2005 that are available via the SQL Server Native Client via connection string keywords or OLE DB properties or Transact-SQL. For more information about the use of these features with ADO, see Using ADO with SQL Server Native Client.
SQL Server Native Client was designed to provide a simplified method of gaining native data access to SQL Server using either OLE DB or ODBC. It is simplified in that it combines OLE DB and ODBC technologies into one library, and it provides a way to innovate and evolve new data access features without changing the current Windows DAC components, which are now part of the Microsoft Windows platform.
While SQL Server Native Client uses components in Windows DAC, it is not explicitly dependant on a particular version of Windows DAC. You can use SQL Server Native Client with the version of Windows DAC that is installed with any operating system supported by SQL Server Native Client.