PHP + MySQL事务示例

我真的没有发现正常的PHP文件的例子，MySQL事务正在使用。你能举个简单的例子吗?

还有一个问题。我已经做过很多编程，没有使用过事务。我可以在header.php中放置一个PHP函数或其他东西，如果一个mysql_query失败，那么其他的也会失败吗?

我想我已经弄明白了，对吗?:

mysql_query("SET AUTOCOMMIT=0");
mysql_query("START TRANSACTION");


$a1 = mysql_query("INSERT INTO rarara (l_id) VALUES('1')");
$a2 = mysql_query("INSERT INTO rarara (l_id) VALUES('2')");


if ($a1 and $a2) {
mysql_query("COMMIT");
} else {
mysql_query("ROLLBACK");
}
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小开
最佳答案

我在处理事务时通常使用的想法是这样的(semi-pseudo-code):

try {
// First of all, let's begin a transaction
$db->beginTransaction();
    

// A set of queries; if one fails, an exception should be thrown
$db->query('first query');
$db->query('second query');
$db->query('third query');
    

// If we arrive here, it means that no exception was thrown
// i.e. no query has failed, and we can commit the transaction
$db->commit();
} catch (\Throwable $e) {
// An exception has been thrown
// We must rollback the transaction
$db->rollback();
throw $e; // but the error must be handled anyway
}

注意，根据这种想法，如果查询失败，必须抛出一个Exception:
    PDO可以做到这一点，这取决于您如何配置它
  • 否则，使用一些其他API，您可能必须测试用于执行查询的函数的结果，并自己抛出异常。

不幸的是，这里面没有魔法。您不能只是在某个地方放置一条指令，然后自动完成事务:您仍然必须指定必须在事务中执行哪组查询。

例如，你经常会在事务(在begin之前)之前有几个查询，在事务(在__ABC1或rollback之后)之后有另外几个查询，你会希望无论事务中发生了什么(或不)，这些查询都被执行。

小开

我想我已经弄明白了，对吗?：

mysql_query("START TRANSACTION");


$a1 = mysql_query("INSERT INTO rarara (l_id) VALUES('1')");
$a2 = mysql_query("INSERT INTO rarara (l_id) VALUES('2')");


if ($a1 and $a2) {
mysql_query("COMMIT");
} else {
mysql_query("ROLLBACK");
}
小开 
<?php


// trans.php
function begin(){
mysql_query("BEGIN");
}


function commit(){
mysql_query("COMMIT");
}


function rollback(){
mysql_query("ROLLBACK");
}


mysql_connect("localhost","Dude1", "SuperSecret") or die(mysql_error());


mysql_select_db("bedrock") or die(mysql_error());


$query = "INSERT INTO employee (ssn,name,phone) values ('123-45-6789','Matt','1-800-555-1212')";


begin(); // transaction begins


$result = mysql_query($query);


if(!$result){
rollback(); // transaction rolls back
echo "transaction rolled back";
exit;
}else{
commit(); // transaction is committed
echo "Database transaction was successful";
}


?>
小开

请检查您正在使用的存储引擎。如果是MyISAM，则不支持Transaction('COMMIT','ROLLBACK')，因为只有InnoDB存储引擎支持事务，而不是MyISAM。

小开

由于这是谷歌上的第一个结果“php mysql事务”，我想我应该添加一个答案，显式地演示如何使用mysqli(原作者想要的例子)。下面是一个PHP/mysqli事务的简化示例:

// let's pretend that a user wants to create a new "group". we will do so
// while at the same time creating a "membership" for the group which
// consists solely of the user themselves (at first). accordingly, the group
// and membership records should be created together, or not at all.
// this sounds like a job for: TRANSACTIONS! (*cue music*)


$group_name = "The Thursday Thumpers";
$member_name = "EleventyOne";
$conn = new mysqli($db_host,$db_user,$db_passwd,$db_name); // error-check this


// note: this is meant for InnoDB tables. won't work with MyISAM tables.


try {


$conn->autocommit(FALSE); // i.e., start transaction


// assume that the TABLE groups has an auto_increment id field
$query = "INSERT INTO groups (name) ";
$query .= "VALUES ('$group_name')";
$result = $conn->query($query);
if ( !$result ) {
$result->free();
throw new Exception($conn->error);
}


$group_id = $conn->insert_id; // last auto_inc id from *this* connection


$query = "INSERT INTO group_membership (group_id,name) ";
$query .= "VALUES ('$group_id','$member_name')";
$result = $conn->query($query);
if ( !$result ) {
$result->free();
throw new Exception($conn->error);
}


// our SQL queries have been successful. commit them
// and go back to non-transaction mode.


$conn->commit();
$conn->autocommit(TRUE); // i.e., end transaction
}
catch ( Exception $e ) {


// before rolling back the transaction, you'd want
// to make sure that the exception was db-related
$conn->rollback();
$conn->autocommit(TRUE); // i.e., end transaction
}

另外，请记住PHP 5.5有一个新方法mysqli: begin_transaction。但是，PHP团队还没有将其记录下来，我仍然停留在PHP 5.3中，所以我不能对此进行评论。

小开

我有这个，但不确定这是否正确。也可以试试这个。

mysql_query("START TRANSACTION");
$flag = true;
$query = "INSERT INTO testing (myid) VALUES ('test')";


$query2 = "INSERT INTO testing2 (myid2) VALUES ('test2')";


$result = mysql_query($query) or trigger_error(mysql_error(), E_USER_ERROR);
if (!$result) {
$flag = false;
}


$result = mysql_query($query2) or trigger_error(mysql_error(), E_USER_ERROR);
if (!$result) {
$flag = false;
}


if ($flag) {
mysql_query("COMMIT");
} else {
mysql_query("ROLLBACK");
}

http://www.phpknowhow.com/mysql/transactions/

小开

我做了一个函数来获取查询向量并进行交易，也许有人会发现它有用:

function transaction ($con, $Q){
mysqli_query($con, "START TRANSACTION");


for ($i = 0; $i < count ($Q); $i++){
if (!mysqli_query ($con, $Q[$i])){
echo 'Error! Info: <' . mysqli_error ($con) . '> Query: <' . $Q[$i] . '>';
break;
}
}


if ($i == count ($Q)){
mysqli_query($con, "COMMIT");
return 1;
}
else {
mysqli_query($con, "ROLLBACK");
return 0;
}
}
小开

另一个mysqli_multi_query的过程风格示例，假设$query由分号分隔的语句填充。

mysqli_begin_transaction ($link);


for (mysqli_multi_query ($link, $query);
mysqli_more_results ($link);
mysqli_next_result ($link) );


! mysqli_errno ($link) ?
mysqli_commit ($link) : mysqli_rollback ($link);
小开

使用PDO连接时:

$pdo = new PDO('mysql:host=localhost;dbname=mydb;charset=utf8', $user, $pass, [
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, // this is important
]);

我经常使用以下代码进行事务管理:

function transaction(Closure $callback)
{
global $pdo; // let's assume our PDO connection is in a global var


// start the transaction outside of the try block, because
// you don't want to rollback a transaction that failed to start
$pdo->beginTransaction();
try
{
$callback();
$pdo->commit();
}
catch (Exception $e) // it's better to replace this with Throwable on PHP 7+
{
$pdo->rollBack();
throw $e; // we still have to complain about the exception
}
}

使用的例子:

transaction(function()
{
global $pdo;


$pdo->query('first query');
$pdo->query('second query');
$pdo->query('third query');
});

这样，事务管理代码就不会在整个项目中重复。这是一件好事，因为从这篇文章中其他与pdo相关的回答来看，它很容易犯错误。最常见的是忘记重新抛出异常并在try块内启动事务。


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