Interview Oracle Frequently asked a question-transaction

Interview these days, (during the interview, did not prepare anything, because recently very tired, brought a body past, basically did not take the brain)
Well, we're pretty much on the technical side.

Let me ask you one more question.

A transaction in Oracle?

You talk to me about business.

I go, business, what do you want to know about business?

Four features of a transaction?

What do you do for a business?

Or what?

Transaction

The interviewer is very faint to say, business is a simple point of content ah, you tell me about business;

I say elder brother, you want to know what affairs, the aspect of affairs;

I really don't know what he wants to know!
And then the interviewer just left.

(In fact, on the road, think slowly to think of a lot of things)

Let's talk about business first!

What is a transaction:

In a database, a transaction is a logical unit in which a database is running, and a transaction consists of one or more SQL statements that complete a set of related behaviors, ensuring that the operations of this set of SQL statements are executed completely successfully, complete the work unit operation, or not at all, through a transaction mechanism.
Key Features: Ensure database integrity.

A transaction has four features: (many people call the acid property of a transaction)

for a set of SQL statement operations that comprise transactions, the database operating system must ensure that these operations are atomic, consistent, isolated, and persistent.
1. atomicity (atomicity)
The atomicity of a transaction is that all the operations contained in a transaction are either done or not, meaning that all activities are either reflected in the database or all are not reflected to ensure database consistency.
2. Consistency (consistency)
Transactional consistency refers to the fact that the database must meet the rule constraints of the business before and after transaction operations.
3. Isolation (Isolation)
Isolation is the ability of a database to allow multiple concurrent transactions to read and write or modify data at the same time, which prevents inconsistencies in data due to the cross-execution of their operations commands when multiple transactions are executed concurrently.
4. Persistence (Durability)
The persistence of a transaction is that after the transaction is finished, its modification to the data should be permanent. Even if the system is not lost in the event of a failure, this is the importance of the data determined.

Interview Oracle Frequently asked a question-transaction