Two types of missing updates

Category 1 lost updates

When transaction A is canceled, the updated data of transaction B that has been committed is overwritten. This error may cause serious problems. You can see it through the following account withdrawal transfer:

Time	Withdrawal transaction	Transfer transaction B
T1	Start transaction
T2		Start transaction
T3	The account balance is USD 1000.
T4		The account balance is USD 1000.
T5		Remit 100 yuan to change the balance to 1100 yuan
T6		Commit transactions
T7	Retrieve 100 yuan and change the balance to 900 yuan
T8	Cancel transaction
T9	Balance restored to 1000 Metadata (lost updates)

When transaction A revokes the transaction, it accidentally erased the amount that transaction B has transferred to the Account.
Type 2 lost updates
Transaction A overwrites the data already submitted by transaction B, resulting in the loss of operations performed by transaction B:

Time	Transfer transaction	Withdrawal transaction B
T1		Start transaction
T2	Start transaction
T3		The account balance is USD 1000.
T4	The account balance is USD 1000.
T5		Retrieve 100 yuan and change the balance to 900 yuan
T6		Commit transactions
T7	Import 100 RMB
T8	Commit transactions
T9	Change balance to 1100 Metadata (lost updates)

In the above example, the check transfer transaction overwrites the withdrawal transaction's updates to the deposit balance, resulting in the Bank's final loss of 100 yuan. On the contrary, if the transfer transaction is committed first, the user account will lose 100 yuan.