all rows have the status NotModified! or New! !!
F:if rows' update status are newmodified, which will they be changed to ? notmodified?
S:if row's update status is new! ,which will be ?
When a row is changed, inserted, or deleted, its update flag is set, making it marked for update. By default the Update method turns these flags off. However, if you want to coordinate updates of more than one DataWindow or DataStore, you can prevent Update from clearing the flags. Then after you verify that all the updates succeeded, you can call ResetUpdate for each DataWindow to clear the flags. If one of the updates failed, you can keep the update flags, prompt the user to fix the problem, and try the updates again.
You can find out which rows are marked for update with the GetItemStatus method. If a row is in the delete buffer or if it is in the primary or filter buffer and has NewModified! or DataModified! status, its update flag is set. After update flags are cleared, all rows have the status NotModified! or New! and the delete buffer is empty.