如何将 PDO 的 execute($variable) 转换为 MySQLi 语句

Question

我正在学习使用 PDO 的教程，我必须使用 MySQLi。在教程中，有这一行：

$stmt->execute(array_keys($products_in_cart));

我最好的尝试是这样做：

$stmt->bind_param('i', array_keys($products_in_cart));

$stmt->execute();

这有效，但仅适用于一种产品，即当数组仅包含一个元素 ([0] => 1) 时。

这是整个部分：

// Check the session variable for products in cart

$products_in_cart = isset($_SESSION['cart']) ? $_SESSION['cart'] : array();

$products = array();

$subtotal = 0.00;

// If there are products in cart

if ($products_in_cart) {

    // There are products in the cart so we need to select those products from the database

    // Products in cart array to question mark string array, we need the SQL statement to include IN (?,?,?,...etc)

    $array_to_question_marks = implode(',', array_fill(0, count($products_in_cart), '?'));

    $stmt = $mysqli->prepare('SELECT * FROM products WHERE id IN (' . $array_to_question_marks . ')');

    // We only need the array keys, not the values, the keys are the id's of the products

    $stmt->bind_param('i', array_keys($products_in_cart));

    $stmt->execute();

    // Fetch the products from the database and return the result as an Array

    $products = $stmt->get_result()->fetch_all(MYSQLI_ASSOC);

    // Calculate the subtotal

    foreach ($products as $product) {

        $subtotal += (float) $product['price'] * (int) $products_in_cart[$product['id']];

    }

}

我相信当有多个产品时，SQL 语句会因 IN() 子句而变得混乱，即$array_to_question_marks不正确。

Answer 1

MySQLi 比 PDO 更难。我强烈建议尽可能使用 PDO。如果你想在 mysqli 中绑定未知数量的参数，你需要创建带有类型的字符串，然后展开数组。$arrayKeys = array_keys($products_in_cart);$stmt->bind_param(str_repeat("s", count($arrayKeys)), ...$arrayKeys);$stmt->execute();