ZEND PHP 5 Certification STUDY GUIDE

168 ” Database Programming
Transactions With mysqli
The mysqli extension implements transaction functionality with the * commit and
*rollback methods. By default, mysqli runs in auto-commit mode, which means
that each database statement will be committed immediately. To disable this functionality
and begin a transaction, set the auto-commit mode to FALSE using the
*autocommit methods. Please note that the * autocommit methods will not work with
non-transactional table types, such as MyISAM or ISAM. For these table types, all
database statements are always committed immediately. See the Transactions section
earlier in this chapter for more information on how transactions work.
The following code illustrates the use of the transactions with mysqli. If any of the
statements executed against the database fail, then the call to mysqli::commit() or
mysqli_commit() will return FALSE. In this case, you can call the * rollback methods to
ensure that any actions taken during the transaction are rolled back and discarded.
Here, one of the INSERT statements fails to list all columns for which it has values.
Thus, the commit fails and the valid INSERT statement executed earlier is not committed
to the database.
$mysqli->autocommit(FALSE);
$mysqli->query("INSERT INTO book (isbn, title, author_id, publisher_id)
VALUES (’0395974682’, ’The Lord of the Rings’, 1, 3)");
$mysqli->query("INSERT INTO book (title) VALUES (’Animal Farm’, 3, 2)");
if (!$mysqli->commit()) {
$mysqli->rollback();
}
The procedural version of the code is very similar:
Licensed to 482634 - Amber Barrow (itsadmin@deakin.edu.au)
mysqli_autocommit($dbh, FALSE);
mysqli_query($dbh, "INSERT INTO book (isbn, title, author_id, publisher_id)
VALUES (’0395974682’, ’The Lord of the Rings’, 1, 3)");
mysqli_query($dbh, "INSERT INTO book (title) VALUES (’Animal Farm’, 3, 2)");
if (!mysqli_commit($dbh)) {
mysqli_rollback($dbh);
}