如何在mysqli中开始和结束交易？

Question

据我所知,事务一旦调用$mysqli->autocommit(FALSE);语句就开始,并在调用$mysqli->commit();命令后结束,如下例所示.

<?php
//Start transaction 
$mysqli->autocommit(FALSE);
$mysqli->query('UPDATE `table` SET `col`=2');
$mysqli->query('UPDATE `table1` SET `col1`=3;');
$mysqli->commit();
//End transaction

//Executing other queries without transaction control
$mysqli->query("Select * from table1");
$mysqli->query("Update table1 set col1=2");
//End of executing other queries without transaction control

//Start transaction 
$mysqli->autocommit(FALSE);
$mysqli->query('UPDATE `table` SET `col`=2');
$mysqli->query('UPDATE `table1` SET `col1`=3;');
$mysqli->commit();
//End transaction
?>

我理解正确吗？如果没有,请你纠正我,因为这实际上是我第一次在现实生活中使用交易.

谢谢.

Answer 1

除了丢弃表外,j0k主要是正确的.

使用 - > commit()不会打开自动提交

相反,DROP TABLE是一个DDL查询,并且DDL查询总是被隐式提交,并将提交所有以前未提交的工作.

因此,如果您未提交工作,则DDL查询将强制执行此提交.

Answer 2

那么根据php doc,你是对的.

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

/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());
    exit();
}

$mysqli->query("CREATE TABLE Language LIKE CountryLanguage");

/* set autocommit to off */
$mysqli->autocommit(FALSE);

/* Insert some values */
$mysqli->query("INSERT INTO Language VALUES ('DEU', 'Bavarian', 'F', 11.2)");
$mysqli->query("INSERT INTO Language VALUES ('DEU', 'Swabian', 'F', 9.4)");

/* commit transaction */
$mysqli->commit();

/* drop table */
$mysqli->query("DROP TABLE Language");

/* close connection */
$mysqli->close();
?>

在上面的例子中:

• 的CREATE TABLE是自动提交,因为它是默认的行为.
• 在INSERT INTO 没有自动致力于因为autocommit(FALSE)
• 的DROP TABLE是自动提交,因为autocommit(FALSE)被重置了通过->commit();.

Answer 3

如何在mysqli中使用事务？

先决条件

为了使事务正常运行，您应该启用异常错误报告。否则mysqli不会报错，事务也不会正确执行。或者，您可以手动检查每个查询，但不建议这样做。要与 mysqli 正确连接，请使用以下 3 行：

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli('localhost', 'user', 'pass', 'dbname');
$mysqli->set_charset('utf8mb4'); // always set the charset

交易

使用 mysqli 创建事务有两种可能的方法。默认情况下，所有查询/语句在执行后立即提交。您可以关闭自动提交或使用一次性事务。

在以下情况下，事务将提交到数据库：

• 打电话时 commit
• 设置 autocommit=1 后
• 开始另一笔交易时
• 执行 DDL 查询时
• 在其他一些情况下。有关更多信息，请参阅导致隐式提交的语句

使用自动提交（假）

如果关闭自动提交，您可以决定何时提交，但调用commit()不会重新打开自动提交。

//Start transaction
$mysqli->autocommit(false);

$mysqli->query('INSERT INTO director(name) VALUE("Steven Spielberg")');

$directorId = $mysqli->insert_id;
$movieTitle = 'Jurassic Park';
$stmt = $mysqli->prepare('INSERT INTO movie(title, directorId) VALUE(?,?)');
$stmt->bind_param('ss', $movieTitle, $directorId);
$stmt->execute();

$mysqli->commit();
// Changes are committed, but autocommit is not switched back on

// Following queries are still transactional. They will not be committed unless you call commit or switch autocommit back on
$mysqli->query('INSERT INTO director(name) VALUE("James Cameron")');

$directorId = $mysqli->insert_id;
$movieTitle = 'Titanic';
$stmt = $mysqli->prepare('INSERT INTO movie(title, directorId) VALUE(?,?)');
$stmt->bind_param('ss', $movieTitle, $directorId);
$stmt->execute();

$mysqli->autocommit(true);
// All queries are committed and everything that follows will be immediately committed.

使用 begin_transaction()

您可以使用 启动一次性事务begin_transaction()。autocommit=false当你打电话commit()结束交易而不开始新的交易时，这不会设置。

//Start transaction 
$mysqli->begin_transaction();

$mysqli->query('INSERT INTO director(name) VALUE("Steven Spielberg")');

$directorId = $mysqli->insert_id;
$movieTitle = 'Jurassic Park';
$stmt = $mysqli->prepare('INSERT INTO movie(title, directorId) VALUE(?,?)');
$stmt->bind_param('ss', $movieTitle, $directorId);
$stmt->execute();

$mysqli->commit();
// Changes are committed and the transaction has ended

// Following queries will be committed one by one as soon as they are peformed.
$mysqli->query('INSERT INTO director(name) VALUE("James Cameron")');

$directorId = $mysqli->insert_id;
$movieTitle = 'Titanic';
$stmt = $mysqli->prepare('INSERT INTO movie(title, directorId) VALUE(?,?)');
$stmt->bind_param('ss', $movieTitle, $directorId);
$stmt->execute();

执行 DDL 语句

某些 SQL 语句会触发显式提交，但不会影响 的值autocommit。

//Start transaction 
$mysqli->autocommit(false);

$mysqli->query('INSERT INTO director(name) VALUE("Steven Spielberg")');

$directorId = $mysqli->insert_id;
$movieTitle = 'Jurassic Park';
$stmt = $mysqli->prepare('INSERT INTO movie(title, directorId) VALUE(?,?)');
$stmt->bind_param('ss', $movieTitle, $directorId);
$stmt->execute();

// The following will call commit but it will not set autocommit=true
$mysqli->query('TRUNCATE TABLE movie_genre');
// if you want to switch autocommit back on, you have to call: 
$mysqli->autocommit(true);

回滚

如果发生异常，PHP 将结束脚本的执行并且代码永远不会到达commit语句。但是，在某些情况下，您可能希望显式回滚事务，例如避免在代码中的其他地方意外调用 commit。

以下是此类交易的示例。第二个查询试图插入一个不存在的表，这意味着 mysqli 将抛出异常。我们没有让 PHP 脚本死掉，而是捕获异常并回滚事务。该值4永远不会插入到数据库中，因为两个查询都已回滚。

try {
    // Start transaction
    $mysqli->begin_transaction();

    $mysqli->query('INSERT INTO some_table(col2) VALUE(4)');
    $mysqli->query('INSERT INTO does_not_exist(col2) VALUE(4)');

    // Commit changes
    $mysqli->commit();
} catch (\Throwable $e) {
    // Something went wrong. Rollback
    $mysqli->rollback();
    // Rethrow the exception so that PHP does not continue with the execution and the error can be logged in the error_log
    throw $e;
}

Answer 4

准备SQL语句ONCE,然后执行多次:

<?php
$Mysqli = new mysqli("host","user","pass","base");

// check connection
if(mysqli_connect_errno())
{
  printf("Connect failed: %s\n",mysqli_connect_error());
  exit();
}

// some data for db insertion
$countries=['Austria','Belgia','Croatia','Denmark','Estonia'];

// explicitly begin DB transaction
$Mysqli->begin_transaction();

// prepare statement (for multiple inserts) only once
$stmt=$Mysqli->prepare("INSERT INTO table(column) VALUES(?)");

// bind (by reference) prepared statement with variable $country
$stmt->bind_param('s',$country);

// load value from array into referenced variable $country
foreach($countries as $country)
{
  //execute prep stat more times with new values
  //$country is binded (referenced) by statement
  //each execute will get new $country value
  if(!$stmt->execute())
  {
    // rollback if prep stat execution fails
    $Mysqli->rollback();
    // exit or throw an exception
    exit();
  }
}

// close prepared statement
$stmt->close();

// commit transaction
$Mysqli->commit();

// close connection
$Mysqli->close();

?>

Answer 5

您认为命令"commit"会自动将autocommit切换回true吗？php doc中的评论说不!