See
http://www.bobswart.nl/Weblog/Blog.aspx?RootId=5:3873There's a change in the SQL Server DBX4 driver for Delphi and C++Builder 2010, which not all developers may have noticed.
The readme.htm states in the Database Changes section for dbExpress, the following:
"MSSQL driver requires the installation of the SQL Native Client. SQL Native Client 2008 is required for dbxmss.dll. SQL Native Client 2005 is required for dbxmss9.dll"
This can be overlooked easily, especially since the Supported Servers section lists - among others - the following for dbExpress:
"Microsoft SQL Server 2008, 2005, 2000 (Ent) (Driver dbxMSS.dll, Client oledb.dll)"
Which makes it look like we can still use oledb.dll as client.
However, if you try to make a connection using DBX4 to a SQL Server database with Delphi or C++Builder 2010, you'll see the error message: "DBX Error: Driver could not be properly initialized. Client library may be missing, not installed properly, or of the wrong version."
For SQL Server 2008, you can download the SQL Native Client from
http://www.microsoft.com/downloads/details.aspx?FamilyId=C6C3E9EF-BA29-4A43-8D69-A2BED18FE73C&displaylang=en"Microsoft SQL Server 2008 Native Client (SQL Native Client) is a single dynamic-link library (DLL) containing both the SQL OLE DB provider and SQL ODBC driver. It contains run-time support for applications using native-code APIs (ODBC, OLE DB and ADO) to connect to Microsoft SQL Server 2000, 2005, or 2008. SQL Native Client should be used to create new applications or enhance existing applications that need to take advantage of new SQL Server 2008 features. This redistributable installer for SQL Native Client installs the client components needed during run time to take advantage of new SQL Server 2008 features, and optionally installs the header files needed to develop an application that uses the SQL Native Client API."
Note by the way, that if you use SQL Server 2008 on Windows 7, you need to apply Service Pack 1, because you may otherwise encounter "compatibility issues" (like permission problems and being unable to alter existing tables.