What are the four characteristics of correctly executing database transactions?

Answer: During data write or update, the database management system (DBMS) must meet the following requirements: Atomicity, Consistency, Isolation, and Durability (ACID) to ensure that transactions are correctly executed.

• Atomicity: also called indivisibility. All operations in a transaction are either completed or not completed, and do not end in an intermediate phase. If an error occurs during transaction execution, the transaction is rolled back to the state before the transaction starts, just as if the transaction has never been executed.
• Consistency: The database integrity is not damaged before and after a transaction starts. This means that the written data must fully comply with all preset rules, including the accuracy of the data, the serialization of the data, and the spontaneous completion of the scheduled work by the subsequent database.
• Isolation: also called independence. Transactions are often executed concurrently. Isolation ensures that concurrent execution of transactions leaves the database in the same state that would have been obtained if the transactions were executed sequentially. Transaction isolation is divided into different levels, including read uncommitted, read committed, repeatable read, and serializable.
• Durability: Once a transaction has been committed, it will remain committed even in the case of a system failure.