Could you explain what is meant by transactions in the context of SQL and how they ensure data integrity?

A transaction in SQL is a sequence of operations on a database that are executed as a single unit. The transaction either completes successfully (commit) or is completely rolled back if an error occurs.

This ensures data integrity because:

• All changes within the transaction are only visible after it successfully completes.
• In case of failure, the database is restored to its state before the transaction began, preventing partial changes.

For example, when transferring money between accounts, it is important that the debit from one account and the credit to another happen together or not at all — a transaction guarantees this.