Can you give an example of a situation where a database maintains data consistency?

Data consistency in a database means that after a transaction is completed, all data remains in a correct and logically consistent state.

Example scenario:

Imagine a banking system where money is transferred from one account to another. The transaction involves two steps:

1. Deduct the amount from one account.
2. Credit the amount to the other account.

If the transaction completes fully, the balances of both accounts will be correct, and the total amount of money in the system will not change. If a failure occurs after the deduction but before the credit, the database will roll back the changes to maintain consistency.

Thus, the database maintains consistency, ensuring that either all operations of the transaction are executed or none are.