Final answer:
The statement regarding all actions in an atomic transaction being completed successfully or not at all is true. This principle is part of the ACID properties and is applicable to all database transactions, not just financial ones.
Step-by-step explanation:
The statement that all actions in an atomic transaction are completed successfully or none of the actions are completed at all is true. An atomic transaction is a fundamental concept in database management and transaction processing systems, ensuring that a series of operations are all completed successfully for the transaction to be committed, or if any action fails, then all actions are rolled back to maintain data integrity. This property is part of what is known as ACID (Atomicity, Consistency, Isolation, Durability) which ensures database transactions are processed reliably. This principle is not exclusive to financial transactions but applies to all types of database transactions.