Do these plural ‘states’ and ‘deadlocks’ mean that multiple inconsistent states and multiple deadlocks may occur? If they were singular (an inconsistent state, a deadlock) then would there be only one of them at a time, please?
If we do not use locking, or if we unlock data items too soon after
reading or writing them, we may get inconsistent states. On the
other hand, if we do not unlock a data item before requesting a lock
on another data item, deadlocks may occur.
Database System Concepts