MySQL Transactions and ACID Properties Explained

A transaction groups multiple statements into one all-or-nothing unit — the mechanism that keeps a bank transfer from debiting one account without crediting the other. ACID is the theory; InnoDB is the implementation.

Key Points

• Atomicity: all statements succeed or none do
• Consistency: data moves from one valid state to another
• Isolation: concurrent transactions don't corrupt each other
• Durability: once committed, data survives crashes (redo log)
• Usage: START TRANSACTION; UPDATE …; UPDATE …; COMMIT; (or ROLLBACK)
• Only transactional engines like InnoDB provide ACID — MyISAM doesn't