When is it necessary to use transactions to ensure data integrity?

Transactions are used to ensure data integrity when it is necessary to guarantee that a set of operations is completed entirely or not at all. This is important in cases such as:

• Working with multiple related data changes that must be atomic (e.g., deducting money from one account and crediting another).
• Avoiding partial data updates that could lead to inconsistent state.
• In systems with parallel access to prevent race conditions and ensure consistency.

In Python, transactions are often used when working with databases through ORM or drivers, for example, using a context manager:

with connection.transaction():
    # multiple database operations
    cursor.execute("UPDATE accounts SET balance = balance - 100 WHERE id = 1")
    cursor.execute("UPDATE accounts SET balance = balance + 100 WHERE id = 2")

If one operation fails, all changes are rolled back, maintaining data integrity.