Preview
IB DP Computer Science — A3 Databases — Database programming | HL | A3.3.6
📋 What You Will Learn
- Describe what a database transaction is and why multi-step changes need one
- Describe each ACID property — atomicity, consistency, isolation, durability — with a concrete failure it prevents
- Construct transaction control language (TCL): BEGIN TRANSACTION, COMMIT, ROLLBACK
- Trace the state of the data through a committed and a rolled-back transaction
- Explain how transactions protect integrity when many users work concurrently
🏦 Why This Matters Moving £200 between bank accounts is two separate updates — subtract here, add there. If the system dies between them, £200 evaporates. A transaction wraps both updates into one all-or-nothing unit: either the whole transfer happens, or it is as if it never started.
Transactions and TCL
📖 Definition — Transaction A