Closing the Cursor
When an application has finished using a cursor, it calls SQLCloseCursor to close the cursor. For example:
Until the application closes the cursor, the statement on which the cursor is opened cannot be used for most other operations, such as executing another SQL statement. For a complete list of functions that can be called while a cursor is open, see Appendix B: ODBC State Transition Tables.
To close a cursor, an application should call SQLCloseCursor, not SQLCancel.
Cursors remain open until they are explicitly closed, except when a transaction is committed or rolled back, in which case some data sources close the cursor. In particular, reaching the end of the result set, when SQLFetch returns SQL_NO_DATA, does not close a cursor. Even cursors on empty result sets (result sets created when a statement executed successfully but which returned no rows) must be explicitly closed.