Database Systems: Concepts, Design and Applications

1.11. Transaction Management

All work that logically represents a single unit is called transaction. The sequence of database operations that represents a logical unit of work is grouped together as a single transaction and access a database and transforms it from one state to another. A transaction can update a record, delete a record, modify a set of records and so on. When the DBMS does a ‘commit’, the changes made by transaction are made permanent. If the changes are not be made permanent, the transaction can be ‘rollback’ and the database will remain in its original state.

When updates are performed on a database, we need some way to guarantee that a set of updates will succeed all at once or not at all. Transaction ensures that all the ...