$insData = array (
        'user_id' => $user_id,
        'request_user_id' => '2',
        'time' => "$time",
        );
    $columns = implode(", ",array_keys($insData));
    $escaped_values = array_values($insData);
    $values  = implode(", ", $escaped_values);
    echo $values;
    $sql = $cn->query("INSERT INTO `connect_request` ($columns) VALUES ($values)");
    if ($sql) {
        echo "Yes";
    }
    else {
        echo " -------- " .$cn->error;
    }