Close connections to ODBC databases.
# S3 method for RODBC close(con, ...)
odbcClose returns a logical indicating if it
succeeded, invisibly unless a warning is given.
close method returns
0 (success) or
RODBC connection object as returned by
additional arguments passed from the generic.
Michael Lapsley and Brian Ripley
odbcClose cleans up and frees resources. It is also the method for the
odbcCloseAll closes all open channels (amongst the first 1000
used in the session).
Channels are closed at the end of an R session, and may also be closed by garbage collection if no object refers to them. In both cases a warning is given (but may not be seen at the end of a console session).