rowid: Row-level lock is not added to the data after running (the data of a row is determined by the physical address), but the data can be edited, and the locking, committing, unlocking and other actions are completed at the moment of committing the transaction, and it is not easy to lock the table.
for update: When the statement is run, a row-level lock is added to the corresponding row (where clause), and no where clause is equivalent to locking the entire table. If the client is disconnected from the network and the tester forgets to submit\roll back the transaction, the lock table will occur.