What concept ensures that all parts of a database transaction are completed successfully?

The concept that ensures all parts of a database transaction are completed successfully is known as Atomicity. This principle is a fundamental aspect of the ACID properties that govern transactions in database management systems.

When a transaction is atomic, it means that it is treated as a single, indivisible unit of work. Hence, either all operations in the transaction are executed or none at all. This prevents a situation where a transaction is partially completed, maintaining the integrity of the database. For instance, if a transaction involves transferring money from one account to another, both the debit and credit operations must succeed for the transaction to be considered successful. If one operation fails, the entire transaction is rolled back, leaving the database in its original state before the transaction began.

In contrast, while the other concepts like Reliability, Consistency, and Durability relate to different aspects of transactions and database reliability, they do not specifically address the requirement for all parts of a transaction to succeed together fundamentally as Atomicity does.