In the PHP world it is common to use an open source database like MySQL for persisting data. But this post is about a less common used database – Oracle – and especially the execution mode found in the PHP OCI extension for Oracle.
The PHP OCI extension for Oracle provides two execution modes: OCI_DEFAULT and OCI_COMMIT_ON_SUCCESS. The default execution mode is OCI_COMMIT_ON_SUCCESS and this mode will automatically commit any (successful) SQL statement. The OCI_DEFAULT mode is mostly used when multiple statements are executed in one batch and should be committed (or rolled back) as one transaction.
Although most PHP developers (and PHP frameworks like Zend Framework) are using the OCI_COMMIT_ON_SUCCESS execution mode as their default mode, I personally think that you should not use this mode: Using the OCI_COMMIT_ON_SUCCESS mode will auto-commit any successful SQL statement, even when a SELECT statement is executed!
Gerton's Corner 