Problems of Concurrent Transactions: Lost Updates
The correct value of X should be 8000, if the initial value is 10000, but the value of X after the execution of both the transactions is 13000. The update made by T3 has been over written by T4. The root cause of the problem was the fact that both the transactions had read the value of X as 10000. Thus one of the two updates has been lost a lost update has occurred.