为什么while循环内的bind_param（）不起作用？ 返回致命错误

Question

Why do bind_param() inside my while loop doesn't work?
I get

Fatal error: Call to a member function bind_param() on a non-object in ...

What I'm going to do here is to show all data from user table (if $key not set) then,
I want to differentiate shown value using if statement. I have tried to execute prepared query in database manager, and it works. But in this case.. my query seems return false. So, any idea? here is the codes,

function cariTemen($key) {
    require 'settings.php';
    $my_id = $_SESSION['user_id'];

    $stmt = $conn->prepare ("SELECT user_id,nama_asli FROM user WHERE username LIKE ? OR nama_asli LIKE ?");
    $key = '%'.$key.'%';
    $stmt->bind_param('ss',$key,$key);
    $stmt->execute();
    $stmt->bind_result($id,$nama);

    //MODIFIED FROM HERE
    while($stmt->fetch()) {
        $temen_id = $id;
        $username = $nama;

        $temen = $conn->prepare("SELECT id_temenan FROM temenan WHERE temen_id = ? AND user_id = ?");
        $temen->bind_param('ii',$temen_id,$my_id); //ERROR IS HERE
        $temen->execute();
        $temen->store_result();
        $jml= $temen->num_rows;

        if($jml > 0) {

            echo $username.' [Temenan]<br>';

        } else {

            echo $username.' <a href="add.php?user_id='.$temen_id.'"">Temenin</a><br>';
        }
    }

    $stmt->close();
}

Thank you in advance for any help you can provide.

as marcellorvalle said that mysql can not maintain 2 simultaneous queries, In this case, i need to store all the values into an array() variable. so the script would be like this :

$user_id = array(); 
$username = array();
$i = 0;

while($stmt->fetch()) {
    $user_id[$i] = $id;
    $username[$i] = $nama;
    $i++;
}

$stmt->close();

for ($j= 0 ; $j <= $i; $j++) {
    $temen = $conn->prepare("SELECT id_temenan FROM temenan WHERE temen_id = ? AND user_id = ?");
    $temen->bind_param('ii',$user_id[$j],$my_id);
    $temen->execute();
    $temen->store_result();
    $jml= $temen->num_rows;

    if($jml > 0) {

        echo  '<a href="profil.php?user_id='.$user_id[$j].'"">'.$username[$j].'</a> [TeMeNan]<br>';

    } else {

        echo ' <a href="profil.php?user_id='.$user_id[$j].'"">'.$username[$j].'</a> <a href="add.php?user_id='.$user_id[$j].'"">[TeMeNin]</a><br>';

    }

}
$temen->close();

Answer 1

1. It is not bind_param() doesn't work but prepare() .
2. It doesn't work because prepared queries are unbuffered by default, and thus in order to run another query while you didn't get all the results from the first one, you have to call store_result() on the first query first.
3. 99 times of 100 when you do a nested query, it means that you should have been running a single query with JOIN

Answer 2

According to the message $temen seems not to be an object. Try to debug it using var_dump($temen). It seems the $conn->prepare is returning false for some reason and false is not an object.

You can check any error echoing $conn->error to see what happened.