Editing Database transaction (section)

===In SQL===
Transactions are available in most SQL database implementations, though with varying levels of robustness. For example, [[MySQL]] began supporting transactions from early version 3.23, but the [[InnoDB]] storage engine was not default before version 5.5. The earlier available storage engine, [[MyISAM]] does not support transactions.

A transaction is typically started using the command <code>BEGIN</code> (although the SQL standard specifies <code>START TRANSACTION</code>). When the system processes a <code>[[Commit (SQL)|COMMIT]]</code> statement, the transaction ends with successful completion.  A <code>[[Rollback (data management)|ROLLBACK]]</code> statement can also end the transaction, undoing any work performed since <code>BEGIN</code>. If [[autocommit]] was disabled with the start of a transaction, autocommit will also be re-enabled with the end of the transaction.

One can set the [[Isolation (database systems)|isolation level]] for individual transactional operations as well as globally. At the highest level (<code>READ COMMITTED</code>), the result of any operation performed after a transaction has started will remain invisible to other database users until the transaction has ended. At the lowest level (<code>READ UNCOMMITTED</code>), which may occasionally be used to ensure high concurrency, such changes will be immediately visible.