Answer
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Work Step by Step
The incorrect summary problem occurs when a transaction reads data that is being modified by another transaction, resulting in an inaccurate summary of the data. For example, suppose there are two transactions: Transaction A reads a balance of $100, and Transaction B updates the balance to 200USD. If Transaction A then calculates a summary based on the initial balance of 100USD, it will produce an incorrect result because it did not account for Transaction B's update.
On the other hand, the lost update problem happens when one transaction overwrites the changes made by another transaction, causing the latter's updates to be lost. For instance, consider two transactions: Transaction X updates a product's quantity to 10, and Transaction Y updates the same product's quantity to 20. If Transaction X's update is applied after Transaction Y's update without considering the latter, the changes made by Transaction Y will be lost, resulting in an incorrect final quantity.
In summary, the key difference lies in the nature of the problem: the incorrect summary problem results in inaccurate summaries of data due to concurrent modifications, while the lost update problem involves one transaction's updates being overwritten by another transaction, leading to lost changes.
