The answer to this question depends on what SDK and what library in that SDK we are talking about. What SDK, and what flash writing library, are you using?
Thank you for your reply. In FDS, I can find the operations about deleting, adding, updating, and queries. About the updating, it says it only delete the former then update the new one. I am not sure if the former info exists.
In order to use fds_record_update(), you need a record descriptor to tell FDS which record you want to update. This means you do need to search for the existing record, for instance through use of fds_record_find(). If you do not find an existing record, you should use fds_record_write() instead.
See for instance how this is done for the Flash Data Storage Example. There you will find relevant code in the function record_update() in the file cli.c. There is also use of fds_record_find() in the main() funciton of main.c, where the record is read, modified and updated (if it exists) or written (if it does not exist, in the else branch.)
