Transaction

• a transaction is the SQL unit of work
• it consists of queries, updates, etc.
• the transaction must end with
  • Commit - store updates made by the transaction
  • Rollback - ignore any updates made by the transaction
• an atomic transaction is one that is either fully executed or fully rolled back

ACID properties

• Atomicity - happens as a whole or none at all
• Consistency - consistency is maintained before and after the consistency
• Isolation - transactions can occur independently of each other simultaneously
• Durability - changes are written to the permanent storage even if power failure occurs during writing