If you want to use transactions with MySQL, you will have to use InnoDB engine, because the default engine on MySQL 5.1 (MyISAM) does not support transactions. Otherwise, if you use MySQL 5.5 you do not have to worry about it, because default engine is InnoDB.

A transaction is a set of SQL instructions which are run as a unit and can be cancelled if it is required.There are confirm and cancel operations

Transactional systems are characterized by their features:

• Atomicity: Transaction’s instructions form a logic unit.

• Coherence: Database must coherent before and after transaction. Can’t affect negatively.

• Isolation: Transactions are not affected among them

• Durability: If the transaction was executed succesfully, changes will be stored permanently.

  To start a transaction you can use BEGIN or START TRANSACTION

  To create a savepoint use SAVEPOINT savepointname

  And for rollback use whether ROLLBACK (to return to the BEGIN point) or ROLLBACK TO savepointname (to return another specific point)

  Example of use:

  

  Example of transactions use with MySQL