Pull Random Data from mySQL

Question

I am trying to pull a random question from one of my tables and display it in HTML. The point is to have the user put in their info in a form, answer the random question that appears, and submit the form that will store the users info along with the question they were asked and their answer. I can't seem to get the question to show up in my HTML and I'm not sure how to fix this. Still new to mySQL.

Code:

<?php

define('DB_NAME', 'db');
define('DB_USER', 'admin');
define('DB_PASSWORD', 'password');
define('DB_HOST', 'localhost');

$link = mysql_connect(DB_HOST, DB_USER, DB_PASSWORD);

if (!$link) {
    die('Could not connect: ' . mysql_error());
}

mysql_select_db('db', $link);

$db_selected = mysql_query("SELECT Question FROM QuestionDB ORDER BY RAND() LIMIT 1");

if (!$db_selected) {
    die('Cant use ' . DB_NAME . ': ' . mysql_error());
}

  if(isSet($_POST['submit'])) {

     $fname = $row['f_name'];
     $lname = $row['l_name'];
     $email = $row['email'];
     $question = $row['question'];
     $answer = $row['answer'];

$sql = "INSERT INTO StudentDB VALUE ( NULL,'$fname','$lname','$email','$question','$answer')";

if (!mysql_query($sql)) {
    die('Error: ' . mysql_error());
}

echo 'Thank you, your information has been sent';
}
else{
echo'

<!DOCTYPE HTML>
<html lang="en">

<head>

</head>

<body>


<form id = "myForm" method="POST">

<div class="col-sm-6" >
<h5><b>First Name: </b><br/><input type="text" name="f_name" size="70"  required></h5>  <br/>
<h5><b> Last Name: </b><br/><input type="text" name="l_name" size="70"  required></h5>  <br/>
</div>
<div class="col-sm-6" >
<h5><b>Email: </b><br/><input type="text" name="email" required></h5><br/>
</div>

<div class="col-sm-12" >
<br/><br/> Question:   ' .$row["Question"]. '
</div>


<div class="col-sm-12" >
<br/><br/>
<h3><b>Answer:</b></h3>
    <textarea maxlength="500" name="comment" id="comment"></textarea><br/>
    </div>

<div class="col-sm-6" >
<input type="submit" name="submit" value="Submit">
</div>
</form>

</body>
</html>';
}
?>

Please dont use the mysql_ database extension, it is deprecated (gone for ever in PHP7) Specially if you are just learning PHP, spend your energies learning the PDO database extensions. Start here — RiggsFolly
– RiggsFolly, Commented May 9, 2016 at 20:20
Your script is at risk of SQL Injection Attack Have a look at what happened to Little Bobby Tables Even if you are escaping inputs, its not safe! — RiggsFolly
– RiggsFolly, Commented May 9, 2016 at 20:20
Just running a mysql_query() does not magically fill a $row variable — RiggsFolly
– RiggsFolly, Commented May 9, 2016 at 20:23
When the user submits data from the page it will be returned to the script in $_POST array variables, not in $row variables. Suggest you sit down and read what you have written and sanity check it — RiggsFolly
– RiggsFolly, Commented May 9, 2016 at 20:24

Smauel · Accepted Answer · 2016-05-10 12:27:36Z

1

On a side note running ORDER BY RAND() is not a good idea. It works to generate a random result, but it adds a lot of overhead which translates into long load times. If you start getting past 100 records you can see this really slow down MySQL queries and lead to long time to first byte wait times by the server. See here: http://www.titov.net/2005/09/21/do-not-use-order-by-rand-or-how-to-get-random-rows-from-table/

answered May 10, 2016 at 12:27

Smauel

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1 Comment

Ken Over a year ago

Thank you, I will look into this.

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