Using native ODBC API I connect to an Excel spreadsheet using Microsoft Excel
Driver (*.xls) 4.00.6305.00 successfully and I am able to create a new table
and insert data into the new table and retrieve the inserted new data
successfully.

While my application is running I can disconnect and reconnect to the Excel
data source and see the new table and its data. However, when my application
exit the new table and inserted data are lost and the spreadsheet is never
updated.

Is there a special ODBC command to close/save an Excel worksheet?

OK. I found out the cause of this issue was a code path that skipped calling
::SQLDisconnect before freeing connection handle. Now it all works