Two processes wating to update the rows of a table which are locked by the other process then deadlock arises. In a database environment this will often happen because of not issuing proper row lock commands. Poor design of front-end application may cause this situation and the performance of server will reduce drastically.

These locks will be released automatically when a commit/rollback operation performed or any one of this processes being killed externally.

Deadlock is a kind of situation,which occured in a network of database environment while multiple processes is waiting for their completion, whereas some other process is still running till the time we use the rollback or commit commands or stopped the blocked process by database systems program itself.