Programming Microsoft Visual C++

The following four database options are supported by DAO:

• Opening an Access database (MDB file)—An MDB file is a self-contained database that includes query definitions, security information, indexes, relationships, and of course the actual data tables. You simply specify the MDB file's pathname.

• Opening an ODBC data source directly—There's a significant limitation here. You can't open an ODBC data source that uses the Jet engine as a driver; you can use only data sources that have their own ODBC driver DLLs.

• Opening an ISAM-type (indexed sequential access method) data source (a group of dBASE, FoxPro, Paradox, Btrieve, Excel, or text files) through the Jet engine—Even if you've set up an ODBC data source that uses the Jet engine to access one of these file types, you must open the file as an ISAM-type data source, not as an ODBC data source.

• Attaching external tables to an Access database—This is actually the preferred way of using DAO to access ODBC data. First you use Access to attach the ODBC tables to an MDB file, and then you use DAO to open the MDB file as in the first option. You can also use Access to attach ISAM files to an MDB file.