beginExternalTransaction() updating;
The beginExternalTransaction method of the ExternalDatabase class starts an external database transaction.
If the external database supports transactions, call this method at the start of a series of updating operations (creates, deletes, or updates) that must be applied atomically to the target database to ensure consistency and the ability to recover.
By default, updates are committed immediately; calling this method delays the commitment of updates until the commitExternalTransaction method is called. If the external database does not support transactions (use the canTransact method to determine this), calling the beginExternalTransaction method has no effect.