An System.Data.Odbc.OdbcConnection object represents a unique connection to a data source created by using a connection string or ODBC data source name (DSN). With a client/server database system, it is equivalent to a network connection to the server. Depending on the functionality supported by the native ODBC driver, some methods or properties of an System.Data.Odbc.OdbcConnection object may not be available.

The System.Data.Odbc.OdbcConnection object uses native resources such as ODBC environment and connection handles. You should always explicitly close any open System.Data.Odbc.OdbcConnection objects by calling OdbcConnection.Close or Dispose before the System.Data.Odbc.OdbcConnection object goes out of scope, or by placing the connection within a Using statement. Not doing this leaves the freeing of these native resources to garbage collection. It might not free them immediately. This, in turn, can eventually cause the underlying driver to run out of resources or reach a maximum limit. This has resulted in intermittent failures. For example, you might experience Maximum Connections -related errors while many connections are waiting to be deleted by the garbage collector. Explicitly closing the connections allows for a more efficient use of native resources, enhancing scalability and improving overall application performance.

If one of the Execute methods of the System.Data.Odbc.OdbcCommand class causes a fatal System.Data.Odbc.OdbcException (for example, a SQL Server severity level of 20 or greater), the System.Data.Odbc.OdbcConnection may close. However, the user can reopen the connection and continue.

An application that creates an instance of the System.Data.Odbc.OdbcConnection object can require all direct and indirect callers to have sufficient permission to the code by setting declarative or imperative security demands. System.Data.Odbc.OdbcConnection creates security demands by using the System.Data.Odbc.OdbcPermission object. Users can verify that their code has sufficient permissions by using the System.Data.Odbc.OdbcPermissionAttribute object. Users and administrators can also use the Code Access Security Policy Tool (Caspol.exe) to modify security policy at the computer, user, and enterprise levels. For more information, see Code Access Security and ADO.NET.

For more information about handling warning and informational messages from the data source, see Working with Connection Events.