回滚以实现原子性和持久性
我试图了解数据库事务的 ACID 属性：它们是如何实现的；哪一部分是原子性，哪一部分是持久性等。
假设我有一个包含两个操作的事务：A 和 B。不幸的是，执行操作 B 时系统已关闭。系统重置后，我们知道数据库将保留（通过 sqlite 中的回滚旅程）执行操作 A 之前的状态。那么，这显示了哪种 ACID 属性，原子性还是持久性？
另一种情况：假设执行action B时，发生错误并通知到应用程序，并回滚应用程序。我认为这是纯粹的原子性，是由用户实现的，而不是由数据库引擎实现的。我说得对吗？
I am trying to understand the ACID property of database transction: how they are achieved; which part is atomicity and which part is durability ,etc.
Let's say I have a transction with two actions,A and B. Unfortunately, system powered off when performing action B. After a system reset, we know the database will preserve (through the rollback jounery in sqlite) the state before performing action A. So, which ACID property does this show, atomicity or durability?
Another case :Suppose when performing action B , an error happened and was notified to the applicaiton , and the application rollback. I consider this is as pure atomicity which is achieved by the user but not by the database engine. Am I correct?
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这两个例子都强调了原子性：A 和 B 要么都提交，要么都不提交。
持久性是一个仅在事务提交之后才出现的属性。应用程序可以放心，如果 COMMIT 调用成功，那么它就是持久的。系统重置或断电不会恢复已提交事务的效果，因此具有持久性。
Both examples highlight atomicity: either both A and B are committed, or neither.
Durability is a property that comes into the picture only after the transaction is committed. The application can rest assured that if the COMMIT call succeeded, then is durable. A system reset or a power off will not revert the effect of a committed transaction, hence its durability.