How can transactions lead to mutual locking in a database?

Deadlocks in a database occur when two or more transactions block resources needed by each other to continue working, and none of them can proceed.

Example: Transaction A has acquired a lock on table 1 and tries to acquire a lock on table 2, while transaction B has already acquired a lock on table 2 and tries to acquire a lock on table 1. Both transactions wait for each other to release resources, leading to a deadlock.

To avoid such situations, databases use detection and resolution mechanisms for deadlocks, such as rolling back one of the transactions, and also recommend following a lock acquisition order and minimizing lock hold times.