Using the Connection Object

A Connection object represents a unique session with a data source. In the case of a client/server database system, it can be equivalent to an actual network connection to the server. Depending on the functionality supported by the provider, some collections, methods, or properties of a Connection object might not be available.

Before opening a Connection object, you must define certain information about the data source and type of connection. The ConnectionString parameter of the Connection object Open method—or the ConnectionString property on the Connection object—usually contains most of this information. A connection string is a string of characters that defines a variable number of arguments. The arguments—some required by ADO, but others provider-specific—contain information that the Connection object must have to carry out its work. The arguments that make up the ConnectionString parameter are separated with semicolons (;).

Note   You can also specify an ODBC Data Source Name (DSN) or a Data Link (UDL) file in a connection string. For more information about DSNs, see Data Sources in Part 1 of the ODBC Programmer's Reference. For more information about UDLs, see Data Link API Overview in the OLE DB Programmer's Reference.