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mysqli::autocommit

mysqli_autocommit

(PHP 5, PHP 7, PHP 8)

mysqli::autocommit -- mysqli_autocommitデータベース更新の自動コミットをオンまたはオフにする

説明

オブジェクト指向型

public mysqli::autocommit(bool $enable): bool

手続き型

mysqli_autocommit(mysqli $mysql, bool $enable): bool

指定されたデータベース接続リソースに対するクエリの 自動コミットモードをオンまたはオフにします。

現在の自動コミットモードを知るには、SQL コマンド SELECT @@autocommit を使用します。

パラメータ

link

手続き型のみ: mysqli_connect() あるいは mysqli_init() が返す mysqliオブジェクト。

enable

自動コミットを有効にするかどうか。

戻り値

成功した場合に true を、失敗した場合に false を返します。

エラー / 例外

mysqli のエラー報告 (MYSQLI_REPORT_ERROR) が有効になっており、かつ要求された操作が失敗した場合は、警告が発生します。さらに、エラー報告のモードが MYSQLI_REPORT_STRICT に設定されていた場合は、mysqli_sql_exception が代わりにスローされます。

例1 mysqli::autocommit() の例

オブジェクト指向型

<?php
/* Tell mysqli to throw an exception if an error occurs */
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);

$mysqli = new mysqli("localhost", "my_user", "my_password", "world");

/* The table engine has to support transactions */
$mysqli->query("CREATE TABLE IF NOT EXISTS language (
Code text NOT NULL,
Speakers int(11) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;"
);

/* Turn autocommit off */
$mysqli->autocommit(false);

$result = $mysqli->query("SELECT @@autocommit");
$row = $result->fetch_row();
printf("Autocommit is %s\n", $row[0]);

try {
/* Prepare insert statement */
$stmt = $mysqli->prepare('INSERT INTO language(Code, Speakers) VALUES (?,?)');
$stmt->bind_param('ss', $language_code, $native_speakers);

/* Insert some values */
$language_code = 'DE';
$native_speakers = 50_123_456;
$stmt->execute();
$language_code = 'FR';
$native_speakers = 40_546_321;
$stmt->execute();

/* Commit the data in the database. This doesn't set autocommit=true */
$mysqli->commit();
print
"Committed 2 rows in the database\n";

$result = $mysqli->query("SELECT @@autocommit");
$row = $result->fetch_row();
printf("Autocommit is %s\n", $row[0]);

/* Try to insert more values */
$language_code = 'PL';
$native_speakers = 30_555_444;
$stmt->execute();
$language_code = 'DK';
$native_speakers = 5_222_444;
$stmt->execute();

/* Setting autocommit=true will trigger a commit */
$mysqli->autocommit(true);

print
"Committed 2 row in the database\n";
} catch (
mysqli_sql_exception $exception) {
$mysqli->rollback();

throw
$exception;
}

手続き型

<?php

/* Tell mysqli to throw an exception if an error occurs */
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);

$mysqli = mysqli_connect("localhost", "my_user", "my_password", "world");

/* The table engine has to support transactions */
mysqli_query($mysqli, "CREATE TABLE IF NOT EXISTS language (
Code text NOT NULL,
Speakers int(11) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;"
);

/* Turn autocommit off */
mysqli_autocommit($mysqli, false);

$result = mysqli_query($mysqli, "SELECT @@autocommit");
$row = mysqli_fetch_row($result);
printf("Autocommit is %s\n", $row[0]);

try {
/* Prepare insert statement */
$stmt = mysqli_prepare($mysqli, 'INSERT INTO language(Code, Speakers) VALUES (?,?)');
mysqli_stmt_bind_param($stmt, 'ss', $language_code, $native_speakers);

/* Insert some values */
$language_code = 'DE';
$native_speakers = 50_123_456;
mysqli_stmt_execute($stmt);
$language_code = 'FR';
$native_speakers = 40_546_321;
mysqli_stmt_execute($stmt);

/* Commit the data in the database. This doesn't set autocommit=true */
mysqli_commit($mysqli);
print
"Committed 2 rows in the database\n";

$result = mysqli_query($mysqli, "SELECT @@autocommit");
$row = mysqli_fetch_row($result);
printf("Autocommit is %s\n", $row[0]);

/* Try to insert more values */
$language_code = 'PL';
$native_speakers = 30_555_444;
mysqli_stmt_execute($stmt);
$language_code = 'DK';
$native_speakers = 5_222_444;
mysqli_stmt_execute($stmt);

/* Setting autocommit=true will trigger a commit */
mysqli_autocommit($mysqli, true);

print
"Committed 2 row in the database\n";
} catch (
mysqli_sql_exception $exception) {
mysqli_rollback($mysqli);

throw
$exception;
}

上の例の出力は以下となります。

Autocommit is 0
Committed 2 rows in the database
Autocommit is 0
Committed 2 row in the database
Autocommit is 0
Committed 2 rows in the database
Autocommit is 0
Committed 2 row in the database

注意

注意:

この関数は、トランザクションに 対応していないテーブル型(MyISAM あるいは ISAM など)では 動作しません。

参考

add a note

User Contributed Notes 4 notes

up
22
jcwebb at dicoe dot com
16 years ago
Just to be clear, autocommit not only turns on/off transactions, but will also 'commit' any waiting queries.
<?php
mysqli_autocommit
($link, FALSE); // turn OFF auto
-some query 1;
-
some query 2;
mysqli_commit($link); // process ALL queries so far
-some query 3;
-
some query 4;
mysqli_autocommit($link, TRUE); // turn ON auto
?>
All 4 will be processed.
up
13
Geoffrey Thubron
16 years ago
It's worth noting that you can perform transactions without disabling autocommit just using standard sql. "START TRANSACTION;" will start a transaction. "COMMIT;" will commit the results and "ROLLBACK;" will revert to the pre-transaction state.

CREATE TABLE and CREATE DATABASE (and probably others) are always commited immediately and your transaction appears to terminate. Thus any commands before and after will be commited, even if a subsequent rollback is attempted.

If you are in the middle of a transaction and you call mysqli_close() it appears that you get the funcitonality of an implicit rollback.

I can't reproduce the "code bug causes lock" problem outlined below (I always get a successful rollback and the script will run umtine times successfully). Therefore, I would suggest that the problem is fixed in php-5.2.2.
up
3
Glen
17 years ago
I've found that if PHP exits due to a code bug during a transaction, an InnoDB table can remain locked until Apache is restarted.

The simple test is to start a transaction by setting $mysqli_obj->autocommit(false) and executing an insert statement. Before getting to a $mysqli_obj->commit statement - have a runtime code bug bomb PHP. You check the database, no insert happened (you assume a rollback occurred) .. and you go fix the bug, and try again... but this time the script takes about 50 seconds to timeout - the insert statement returning with a “1205 - Lock wait timeout exceeded; try restarting transaction”. No rollback occurred. And this error will not go away until you restart Apache - for whatever reason, the resources are not released until the process is killed.

I found that an ‘exit’, instead of a PHP code bug, will not cause a problem. So there is an auto-rollback mechanism in place - it just fails miserably when PHP dies unexpectantly. Having to restarting apache is a pretty drastic measure to overcome a code bug.

To avoid this problem, I use “register_shutdown_function()” when I start a transaction, and set a flag to indicate a transaction is in process (because there is no unregister_shutdown_function()). See below. So the __shutdown_check() routine (I beleive it needs to be public) is called when the script bombs - which is able to invoke the rollback().

these are just the relevant bits to give u an idea...

<?php

public function begin_transaction() {
$ret = $this->mysqli_obj->autocommit(false);
$this->transaction_in_progress = true;
register_shutdown_function(array($this, "__shutdown_check"));
}

public function
__shutdown_check() {
if (
$this->transaction_in_progress) {
$this->rollback();
}
}

public function
commit() {
$ret = $this->mysqli_obj->commit();
$this->transaction_in_progress = false;
}

public function
rollback() {
$ret = $this->mysqli_obj->rollback();
$this->transaction_in_progress = false;
}
?>

True for PHP 5.1.6 + MySQL 5.0.24a.
up
-8
will at phpfever dot com
17 years ago
If you are using the mysql command line tool, here are some helpful hints for the autocommit feature:

1. To view the current autocommit setting, you can use this query: select @@autocommit; It will return the current setting as 1 or 0 (on or off)

2. You can manage the default autocommit feature in you my.cnf or my.ini by adding the following line: init_connect='set autocommit=0'. I'm pretty sure this isn't in the documentation, but it does work.

Here are the current engines, as of MySQL 5.1dev that support transactions:

InnoDB
BerkeleyDB
Falcon

Falcon is very new, so beware using it on production systems.
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