Getting answers from a database - php

Question

I am making an online test script where you can input the answers in the input elements. Once the test is submitted I want the database's answers to be compared with the inputted answers to say whether it is wrong or not, however the script I am using is not working! :S
Here is the problem!
In the database, I have 4 out of 50 ready answers set (not all yet) when I answer both 4 correct or wrong it returns them being incorrect. It lists all the answers, whether they're correct or incorrect in the page but it's not working correctly, no matter what inputs I do, it all the answers up to 49 say incorrect, then for some reason 50 says correct?...
Here is my script:
<?php
$con=mysqli_connect("localhost","dstsbsse","pass","user");
if (mysqli_connect_errno($con))
{
echo "ERROR - Failed to connect to MySQL Server. Please contact an Administrator at English In York: " . mysqli_connect_error();
}
//Set variables to hold output data and total score.
$output="";
$score=0;
//for-next loop. This means "Set n to value one. Every time through the loop (between {}) increase n by one. Do this while n is less than or equal to 50"
for($n=1;$n<=50;$n++)
{
$sql="SELECT a$n FROM answer WHERE 1";
// $sql="SELECT * FROM answer WHERE name='a$n'"; //sql is specific to your table of course - you will need to change this.
$result = $con->query($sql); // perform the query
$row = $result->fetch_assoc(); //load the result into the array $row
$key="a".$n; //concatenate to generate the $_POST keys
if($row['answer']==$_POST[$key]) //compare the data from the table with the answer
{
//answer is correct
$score++;
$output.="Answer $n is correct</BR>"; //add responses to the output string
}
else
{
$output.="Answer $n is incorrect</BR>";
}
}
$output.="Total score: $score/50"; //add the score
echo $output; //echo to screen.
Here is an example of one of the questions answer boxes:
<input type="text" name="a1" id="a1" required>
How can I fix this?

Answer 1

Fetching a query like:
SELECT a1 FROM answer
would return $row['a1'], instead of $row['answer']
So you should be using the column name, not the table one