How can I see if the user's choice in the quiz

I am trying to check if the answer that the user chose was correct, but it doesn't work properly:

                        <form method="post">
                        <?php
                            $question = mysql_query("SELECT * FROM `questions`");
                            $stat = mysql_fetch_assoc($question);
                            $num = mysql_num_rows($question);
                            $questionid = 0;
                            for($i=0;$i<=$num;$i++)
                            {
                                $question = mysql_query("SELECT * FROM `questions` WHERE `id`='$i'");
                                $stat = mysql_fetch_assoc($question);
                                //if($stat['answer'] == null
                                echo $stat['question'] . '<br />';
                                echo '<input type="radio" name="a'.$x.'" value="'.$x.'" />' .$stat['answer1']."<br />";
                                echo '<input type="radio" name="a'.$x.'" value="'.$x.'" />' .$stat['answer2'] . '<br />';
                                echo '<input type="radio" name="a'.$x.'" value="'.$x.'" />' .$stat['answer3'] . '<br />';
                                echo '<input type="radio" name="a'.$x.'" value="'.$x.'" />' .$stat['answer4'] . '<br />';
                                $questionid++;
                                $x = $x+1;
                            }
                            echo $result;
                        ?>
                        <input type="submit" name="go" value="Go" />
                    </form>

That part basically:

$x = 1;
$question = mysql_query("SELECT * FROM `questions`");
$stat = mysql_fetch_assoc($question);
$num = mysql_num_rows($question);
if(isset($_POST['go']))
{
    for($i=0;$i<$num;$i++)
    {
        if ($_POST['ans'.$x] == $row['correct']) 
        { 
            $result = $result + 1; 
        }
        $x = $x + 1;
    }
}

For some reason it doesn't post the results properly and I think something is wrong with the code, would appreciate help.

Here's another attempt at helping you.

I actually wrote a "complete solution", and in the process discovered a few little bugs in your code - plus some things I just couldn't understand.

Principal bug: all your radio buttons have the same value ($x), so no matter what button you press for question 1, the answer is "1", etc. There were other things you did that I could not quite figure out - so what I did instead was create a simple flow - one page that asks the questions, and another that evaluates the results.

Question page (I obfuscated access parameters for my database - no, I don't use "password" as my password!):

<html>
<body>
<form action="./evaluate.php" method="post">
<?php
$server = mysql_connect ('localhost', 'username, 'password');
mysql_select_db("questionnaire", $server);

$question = mysql_query("SELECT * FROM `Questions`;");
$x = 0;
while ($row = mysql_fetch_assoc($question))
{
   echo $row['question'] . '<br />';
   echo '<input type="radio" name="a'.$x.'" value=1 />' .$row['answer1'] . '<br />';
   echo '<input type="radio" name="a'.$x.'" value=2 />' .$row['answer2'] . '<br />';
   echo '<input type="radio" name="a'.$x.'" value=3 />' .$row['answer3'] . '<br />';
   echo '<input type="radio" name="a'.$x.'" value=4 />' .$row['answer4'] . '<br />';
   $x = $x + 1;

}
mysql_close($server);
?>

<input type="submit" name="Submit" value="Submit" />
<br>
</form>
</body>
</html>

and evaluate.php: EDIT: I changed the code a bit to make the output "cleaner", and add a red/green touch to show questions that had been answered correctly and incorrectly. Obviously you can take these things much further if you want...

<html>
<body>

<?php
$server = mysql_connect ('localhost', 'username', 'password');
mysql_select_db("questionnaire", $server);

$question = mysql_query("SELECT * FROM `Questions`;");
$x = 0;
$score = 0;
while ($row = mysql_fetch_assoc($question))
{
    echo $row['question'] . '?<br />';

    $answered = $row['answer'.$_POST['a'.$x]] ;
    $correct = $row['correct'] ;

    if ($answered == $correct ) {
        $score++;
        $acolor = 'green' ;
    }
    else {
        $acolor = 'red' ;
    }

    echo 'you answered <font color=' . $acolor . '>' . $answered . '<font color=black> <br />';


    echo 'the correct answer was ' . $correct . '<br />' ;
    echo '-------------------------------------- <br />' ;

    $x = $x + 1;
}
echo 'You had a total of ' . $score . ' out of ' . $x . ' questions right!';
mysql_close($server);
?>

</body>
</html>

This produced (for a simple three-question multiple choice I made) the expected results. Let me know if it works for you!