脚本一直显示数组到字符串转换错误

I created an array and stored it inside a $_SESSION variable, now I want to include that array inside a MySQL select statement to get more infos depending on p, which is included in my URL. My code is included inside a HTML page, which is completely empty except for necessary HTML and of course session_start, so this is not the problem. The code looks like that:

<?php
$p = $_GET["p"];

var_dump($_SESSION['questions'][$p]);

include("../script/db_connect.php");

$p = $_GET["p"];

$select_right_question = "select * from questions where id = '{$_SESSION['questions'][$p]}'";

$question_infos = mysqli_query($con, $select_right_question);

while ($row = mysqli_fetch_assoc($question_infos)) {
    echo $row["question"] . '</br>'
        . $row["right_answer"] . '</br>'
        . $row["answer2"] . '</br>'
        . $row["answer3"] . '</br>'
        . $row["answer4"];
}

mysqli_close($con);
?>

I already tested it and the main issue is the following line:

$select_right_question = "select * from questions where id = '{$_SESSION['questions'][$p]}'";

What is the correct way to include the SESSION variable here?

Disregarding the security issues with your code, and assuming $_SESSION['questions'][$p] is returning an array, you can modify your SQL statement to:

$select_right_question = "select * from questions where id = '{$_SESSION['questions'][$p]['id']}'";