用web语言mysql数据库完成acoount表学习事务。Bob向Rose转账100元,正常提交状态观察两个账户的余额是否正确。然后异常模拟,当Bob转账后,余额减少了,这时发生异常。观察最后的结果是否正常
时间: 2024-03-07 15:47:43 浏览: 13
好的,以下是针对您的问题的示例代码,使用了PHP语言和MySQL数据库来完成account表的学习事务:
```php
<?php
// 连接MySQL数据库
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "test";
$conn = new mysqli($servername, $username, $password, $dbname);
// 创建account表
$sql = "CREATE TABLE IF NOT EXISTS account (
id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
name VARCHAR(30) NOT NULL,
balance INT(11) NOT NULL
)";
$conn->query($sql);
// 插入两个账户
$sql = "INSERT INTO account (name, balance) VALUES
('Bob', 1000),
('Rose', 0)";
$conn->query($sql);
// 定义转账函数
function transfer_money($from_account, $to_account, $amount, $conn) {
// 开启事务
$conn->query("START TRANSACTION");
// 查询余额
$sql = "SELECT balance FROM account WHERE name = '$from_account'";
$result = $conn->query($sql);
$from_balance = $result->fetch_assoc()['balance'];
if ($from_balance < $amount) {
// 回滚事务
$conn->query("ROLLBACK");
echo "Not enough balance!";
return;
}
$sql = "SELECT balance FROM account WHERE name = '$to_account'";
$result = $conn->query($sql);
$to_balance = $result->fetch_assoc()['balance'];
// 更新余额
$sql = "UPDATE account SET balance = balance - $amount WHERE name = '$from_account'";
$conn->query($sql);
$sql = "UPDATE account SET balance = balance + $amount WHERE name = '$to_account'";
$conn->query($sql);
// 提交事务
$conn->query("COMMIT");
}
// 正常转账
transfer_money('Bob', 'Rose', 100, $conn);
$sql = "SELECT balance FROM account WHERE name = 'Bob'";
$result = $conn->query($sql);
echo "Bob's balance: " . $result->fetch_assoc()['balance'] . "<br>";
$sql = "SELECT balance FROM account WHERE name = 'Rose'";
$result = $conn->query($sql);
echo "Rose's balance: " . $result->fetch_assoc()['balance'] . "<br>";
// 异常模拟
try {
transfer_money('Bob', 'Rose', 1000, $conn);
} catch (Exception $e) {
// 不处理异常
}
$sql = "SELECT balance FROM account WHERE name = 'Bob'";
$result = $conn->query($sql);
echo "Bob's balance: " . $result->fetch_assoc()['balance'] . "<br>";
$sql = "SELECT balance FROM account WHERE name = 'Rose'";
$result = $conn->query($sql);
echo "Rose's balance: " . $result->fetch_assoc()['balance'] . "<br>";
// 关闭连接
$conn->close();
?>
```
在上面的代码中,我们首先连接了MySQL数据库,然后创建了一个名为account的表,并向表中插入了两个账户Bob和Rose。接着定义了一个名为transfer_money的函数,用于执行转账操作。在函数中,我们首先开启了一个事务,然后查询了Bob和Rose的余额,如果Bob的余额不足,则回滚事务,否则更新两个账户的余额,并提交事务。在正常转账和异常模拟后,我们分别查询了Bob和Rose的余额,以确保事务处理的正确性。
请注意,上述代码示例仅供参考,实际使用时需要根据具体的情况进行修改。同时,为了保证安全性,应该使用预处理语句来执行SQL语句,以避免SQL注入攻击。