无法获取上一个查询以进行匹配


Cannot fetch the previous query for matching

<?php
session_start();
include 'connection.php';
 $user_answer = $_POST['answ'];
$random = rand(1, 20);
if(isset($_POST['btn']))
{if ($user_answer == $_SESSION['answer']) {
        echo '<br>RIGHT ANSWER<br>';
    } else {
        echo '<br>WRONG, THE RIGHT ANSWER IS ' . $_SESSION['answer'] . '<br>';
    }
}
$sql = "SELECT Questions,Answers FROM history WHERE questions_id=$random";
$sth = $conn->query($sql);
$sth->execute();
$result = $sth->fetch(PDO::FETCH_ASSOC);
//print_r($result);
echo 'QUESTION: ' . $result['Questions'];
$_SESSION['answer']=$result['Answers'];
?>

你好。我是这个php pdo的新手。我想进行一个查询,以获取问题并检查用户输入的答案。但是我也不能用各种代码来做到这一点。它总是获取下一个问题和答案。SO 给出错误的答案输出。并且有什么方法可以继续会话,导致它重定向到我的主页

我误解了这个问题:请尝试以下操作:

if(isset($_POST['btn']))
{
   if (trim($user_answer) == trim($_SESSION['answer'])) {
        echo '<br>RIGHT ANSWER<br>';
    } else {
        echo '<br>WRONG, THE RIGHT ANSWER IS ' . $_SESSION['answer'] . '<br>';
    }
    unset($_SESSION['answer']);
}

我已经取消设置了会话变量。请尝试此。