databaseDataSet.usertableDataTable deletedChildRecords =
        (databaseDataSet.usertableDataTable)databaseDataSet.usertable.GetChanges(DataRowState.Deleted);

            databaseDataSet.usertableDataTable newChildRecords =
                (databaseDataSet.usertableDataTable)databaseDataSet.usertable.GetChanges(DataRowState.Added);

            databaseDataSet.usertableDataTable modifiedChildRecords =
                (databaseDataSet.usertableDataTable)databaseDataSet.usertable.GetChanges(DataRowState.Modified);

            try
            {
                if (deletedChildRecords != null)
                {
                    usertableTableAdapter.Update(deletedChildRecords);
                }

                usertableTableAdapter.Update(databaseDataSet.usertable);

                if (newChildRecords != null)
                {
                    usertableTableAdapter.Update(newChildRecords);
                }

                if (modifiedChildRecords != null)
                {
                    usertableTableAdapter.Update(modifiedChildRecords);
                }

                databaseDataSet.AcceptChanges();
            }

            catch (Exception ex)
            {
                MessageBox.Show("C'è stato un errore: " + ex);
                // Add code to handle error here.
            }

            finally
            {
                if (deletedChildRecords != null)
                {
                    deletedChildRecords.Dispose();
                }
                if (newChildRecords != null)
                {
                    newChildRecords.Dispose();
                }
                if (modifiedChildRecords != null)
                {
                    modifiedChildRecords.Dispose();
                }
            }
            
            usertableTableAdapter.Update(databaseDataSet.usertable); //Qui viene segnato l'errore