If the database were in an inconsistent state before a transaction, it would remain in the inconsistent state after the transaction.DBMS transactions must be atomic, consistent, isolated and durable.A successful transaction can change the database from one CONSISTENT STATE to another.If the database operations do not update the database but only retrieve data, this type of transaction is called a read-only transaction.The transaction concept in DBMS is executed as a single unit.A transaction is a program unit whose execution may or may not change the contents of a database.Why do you need concurrency in Transactions?.Only once the database is committed the state is changed from one consistent state to another. During the transaction the database is inconsistent. In a nutshell, database transactions represent real-world events of any enterprise.Īll types of database access operation which are held between the beginning and end transaction statements are considered as a single logical transaction in DBMS. A Database Transaction is a logical unit of processing in a DBMS which entails one or more database access operation.

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