在mySQL预处理语句中使用变量

Question

Is it possible to use PHP variables inside a prepared mySQL query, such as:

$stmt = $mysqli->prepare("UPDATE table SET $variable_field = ? WHERE field = ?");

It's being used within an ordering system - such that I have a session that stores the carts contents. I won't know the total number of items ordered until the end. So say a customer orders 10 items - I need to insert those values into item_1, item_2, item_3, etc.

What I would like to achieve:

<<connect to DB>>
$x = 0;
while($x < count($order_contents)) {
    $stmt = $mysqli->prepare("UPDATE table SET item_$x = ? WHERE field = ?");
    $stmt->bind_param("ss", $order_contents[$x], $order_number);
    $stmt->execute();
    $x++;
}
<<close DB connection>>

Pretty much something along those lines. Problem is, I can't see that it's allowing me to specify PHP variables directly within the query. Any help or suggestions?

Answer 1

$x = 0;
while($x < count($order_contents)) {
    $x++;
    $stmt = $mysqli->prepare('UPDATE table SET item_'.$x.' = ? WHERE field = ?');
    $stmt->bind_param("ss", $order_contents[$x], $order_number);
    $stmt->execute();
}

I also moved the $x++ to the start of the loop since you want to start with item_1.