Transactions are a mechanism that ensures data consistency. Transactions have the following four properties −
- Atomicity − Either a transaction completes or nothing happens at all.
- Consistency − A transaction must start in a consistent state and leave the system in a consistent state.
- Isolation − Intermediate results of a transaction are not visible outside the current transaction.
- Durability − Once a transaction was committed, the effects are persistent, even after a system failure.
The Python DB API 2.0 provides two methods to either commit or rollback a transaction.
Example
You already know how to implement transactions. Here is again similar example −
# Prepare SQL query to DELETE required records sql = "DELETE FROM EMPLOYEE WHERE AGE > '%d'" % (20) try: # Execute the SQL command cursor.execute(sql) # Commit your changes in the database db.commit() except: # Rollback in case there is any error db.rollback()