会計システムにカスタム通貨機能を追加する方法 - PHP を使用してカスタム通貨を開発する方法

<?php
// 连接数据库
$db_host = "localhost";
$db_username = "your_username";
$db_password = "your_password";
$db_name = "currency";

$conn = new mysqli($db_host, $db_username, $db_password, $db_name);

// 创建新货币
function createCurrency($name, $symbol, $exchange_rate) {
    global $conn;
    $sql = "INSERT INTO currency_table (name, symbol, exchange_rate) VALUES ('$name', '$symbol', $exchange_rate)";
    $result = $conn->query($sql);
    return $result;
}

// 修改货币信息
function updateCurrency($id, $name, $symbol, $exchange_rate) {
    global $conn;
    $sql = "UPDATE currency_table SET name='$name', symbol='$symbol', exchange_rate=$exchange_rate WHERE id=$id";
    $result = $conn->query($sql);
    return $result;
}

// 删除货币
function deleteCurrency($id) {
    global $conn;
    $sql = "DELETE FROM currency_table WHERE id=$id";
    $result = $conn->query($sql);
    return $result;
}

// 获取所有货币
function getAllCurrencies() {
    global $conn;
    $sql = "SELECT * FROM currency_table";
    $result = $conn->query($sql);
    $currencies = array();

    while ($row = $result->fetch_assoc()) {
        $currency = array(
            "id" => $row["id"],
            "name" => $row["name"],
            "symbol" => $row["symbol"],
            "exchange_rate" => $row["exchange_rate"]
        );
        array_push($currencies, $currency);
    }

    return $currencies;
}

// 兑换货币
function convertCurrency($amount, $from_currency_id, $to_currency_id) {
    global $conn;
    $sql = "SELECT exchange_rate FROM currency_table WHERE id=$from_currency_id";
    $result = $conn->query($sql);
    $from_currency = $result->fetch_assoc();
    $from_exchange_rate = $from_currency["exchange_rate"];

    $sql = "SELECT exchange_rate FROM currency_table WHERE id=$to_currency_id";
    $result = $conn->query($sql);
    $to_currency = $result->fetch_assoc();
    $to_exchange_rate = $to_currency["exchange_rate"];

    $converted_amount = $amount * ($to_exchange_rate / $from_exchange_rate);
    return $converted_amount;
}

// 用法示例
// 创建新货币
createCurrency("My Currency", "MC", 1.5);

// 修改货币信息
updateCurrency(2, "New Currency", "NC", 2.0);

// 删除货币
deleteCurrency(3);

// 获取所有货币
$currencies = getAllCurrencies();
print_r($currencies);

// 兑换货币
$amount = 100;
$from_currency_id = 1;
$to_currency_id = 2;
$converted_amount = convertCurrency($amount, $from_currency_id, $to_currency_id);
echo "Converted amount: " . $converted_amount;
?>