MySQLi的多重条件，有什么不对

Question

I am trying to do prepared statements as follows:

    $stmt = $mysqli->prepare("SELECT COUNT(*) FROM table WHERE from = '?' && to = '?' LIMIT 1");
    $stmt->bind_param('ii', $fromId, $toId);
    $stmt->execute();
    $stmt->bind_result($db_offeredAlready);
    $stmt->fetch();
    $stmt->close();

I get the following error:

 Fatal error: Call to a member function bind_param() on a non-object in /path/to/script.php on line 97

Adding ` and ' gives me

    $stmt = $mysqli->prepare("SELECT COUNT(*) FROM `table` WHERE `from` = '?' && `to` = '?' LIMIT 1");

and the following

 Warning: mysqli_stmt::bind_param() [mysqli-stmt.bind-param]: Number of variables doesn't match number of parameters in prepared statement in /path/to/script.php on line 97

Obviously the number of BIND vars match the number of ? marks. I have tried all combinations of adding and removing ` and ' to no avail. What's wrong with this prepared statement? I can do a SELECT with one condition just fine, but it complains with multiple.

Answer 1

Placeholders (?) need not to be quoted.

$stmt = $mysqli->prepare("SELECT COUNT(*) FROM `table` WHERE `from` = ? && `to` = ? LIMIT 1");