ACID Property - Atomicity Consistency Isolation Durability
A for Atomicity
The principle of atomicity states that all parts of a transaction must complete or not.
C for Consistency
The principle of consistency states that the results of a query must be consistent with the state of the database at the time the query started. It requires that the database ensure that changed values are not seen by the query. Through the use of undo segments Oracle guarantees that if a query succeeds, the result will be consistent to all else data shown from undo segments.
I for Isolation
The principle of isolation states that an incomplete i.e. uncommitted transaction must be invisible to all others. While the transaction is in progress, only the one session that is executing the transaction is allowed to see the changes, all other sessions must see the unchanged data, not the new values.
D for Durability
The principle of durability states that once a transaction completes with a COMMIT, it must be impossible for the database to lose it. During the time that the transaction is in progress, the principle of isolation requires that no one can see the changes it has made so far.
