<?php
$serverName = "serverName\instanceName";
$connectionOptions = array(
    "Database" => "dbName",
    "Uid" => "username",
    "PWD" => "password"
);

$conn = sqlsrv_connect($serverName, $connectionOptions);

if ($conn === false) {
    die(print_r(sqlsrv_errors(), true));
}

// 设置事务隔离级别为SERIALIZABLE（最高隔离级别）
$sql = "SET TRANSACTION ISOLATION LEVEL SERIALIZABLE";
$stmt = sqlsrv_query($conn, $sql);

// 开始事务
if (sqlsrv_begin_transaction($conn) === false) {
    die(print_r(sqlsrv_errors(), true));
}

// 执行需要锁定的操作
$sql = "UPDATE Products SET Stock = Stock - 1 WHERE ProductID = 123";
$stmt = sqlsrv_query($conn, $sql);

if ($stmt === false) {
    sqlsrv_rollback($conn);
    die(print_r(sqlsrv_errors(), true));
}

// 提交事务
sqlsrv_commit($conn);
sqlsrv_close($conn);
?>

<?php
// 使用WITH (TABLOCKX)获取表的排他锁
$sql = "SELECT * FROM Orders WITH (TABLOCKX) WHERE OrderID = 456";

// 使用WITH (ROWLOCK, XLOCK)获取行级排他锁
$sql = "UPDATE Customers WITH (ROWLOCK, XLOCK) SET LastPurchase = GETDATE() WHERE CustomerID = 789";
?>

<?php
$conn = sqlsrv_connect($serverName, $connectionOptions);

// 获取应用程序锁
$sql = "EXEC sp_getapplock @Resource = 'OrderProcessingLock', 
                          @LockMode = 'Exclusive', 
                          @LockOwner = 'Session', 
                          @LockTimeout = 10000"; // 10秒超时

$stmt = sqlsrv_query($conn, $sql);

// 检查是否成功获取锁
if ($stmt === false) {
    die(print_r(sqlsrv_errors(), true));
}

// 执行需要锁定的操作
// ...

// 释放锁
$sql = "EXEC sp_releaseapplock @Resource = 'OrderProcessingLock', @LockOwner = 'Session'";
sqlsrv_query($conn, $sql);
?>

$maxRetries = 3;
$retryCount = 0;
$success = false;

while ($retryCount < $maxRetries && !$success) {
    try {
        // 事务代码
        $success = true;
    } catch (Exception $e) {
        if (strpos($e->getMessage(), 'deadlock') !== false) {
            $retryCount++;
            sleep(1); // 等待1秒后重试
        } else {
            throw $e;
        }
    }
}