Tutorial: How to build a poll system with PHP and mySQL

April 11th, 2008 by VoiDeT | Posted in PHP | With 20,617 views | Word Count: 289 |

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8. Now instead of testing if the form has been submitted and then show the results, we will do much like before and test if the visitor's IP address is in the database already for the given poll. So lets add some code to poll.php.

After:

  1. if($rows > 0){
  2.     $poll = mysql_fetch_array($query);
  3.     $title = $poll['name'];
  4.   } else {
  5.     $title = 'No Poll Yet';
  6.   }

Put:

  1. $query = mysql_query("SELECT `questions`.`pid` FROM  `responses`, `questions` WHERE `responses`.`qid`=`questions`.`id` AND `responses`.`ip`='".$_SERVER['REMOTE_ADDR']."' AND pid='".$poll['id']."'");
  2.  
  3.   if(mysql_num_rows($query) > 0){
  4.  
  5.   } else {

And we need to close that bracket off so at the very end of the file put:

  1. <?php } ?>

Great. So basically like before we are checking if there is an ip address for the poll already. If there is, then the number of rows returned will be over 0, so that part of the code is executed, if it is 0 then we show the original form again. Which reminds me, we need to display those arrays!

Just after this line:

  1. <table width="100%" cellpadding="0" cellspacing="0" border="0">

Put in:

  1. <?php
  2.       if(isset($error)){
  3.     ?>
  4.       <tr>
  5.         <td valign="top" colspan="2" align="center"><?php echo $error; ?></td>
  6.       </tr>
  7.     <?php
  8.       }
  9.     ?>

Now i know what you are thinking. Some of those errors will never be seen. You are right. But with PHP and any programming, you need to account for every scenario. I always program for circumstances that i know might never happen, but if they do, i know that i have my a$$ covered. Its a good mentality to have in order to uphold security. One error will happen to display however, and that is if they don't select an option!

So now that we have our conditional statement checking for ip addresses already who have already submitted a response, lets go about showing these responses. Paste in this code between the brackets of:

  1. if(mysql_num_rows($query) > 0){
  2.  
  3.   } else {

And no, not where the else is!

Paste this in:

  1. $total = mysql_query("SELECT `questions`.`pid` FROM  `responses`, `questions` WHERE `responses`.`qid`=`questions`.`id` AND pid='".$poll['id']."'");
  2.   $total = mysql_num_rows($total);
  3. ?>
  4. <table width="300" cellpadding="0" cellspacing="0" border="0" align="center">
  5.   <tr>
  6.     <td valign="top" align="center"><?php echo $title; ?></td>
  7.   </tr>
  8.   <?php
  9.     $query = mysql_query("SELECT * FROM `questions` WHERE `pid`='".$poll['id']."' ORDER BY `question`");
  10.     $questions = mysql_num_rows($query);
  11.     if($questions > 0){
  12.   ?>
  13.   <tr>
  14.     <td valign="top">
  15.     <table width="100%" cellpadding="0" cellspacing="0" border="0">
  16.       <?php
  17.         while($question = mysql_fetch_array($query)){
  18.           $responses = mysql_query("SELECT count(id) as total FROM `responses` WHERE qid='".$question['id']."'");
  19.           $responses = mysql_fetch_array($responses);
  20.           $percentage = round(($responses['total'] / $total) * 100);
  21.           $percentage2 = 100 - $percentage;
  22.       ?>
  23.         <tr>
  24.           <td valign="top" nowrap="nowrap"><?php echo $question['question']; ?></td>
  25.           <td valign="top" height="10" width="100%">
  26.           <table width="100%" cellpadding="0" cellspacing="0" border="0">
  27.             <tr>
  28.               <td valign="top" width="<?php echo $percentage; ?>%" <?php if($percentage > 0){?>style="background: url('images/bar.jpg') repeat-x;"<?php } ?>><img src="images/dot.gif" width="1" height="19" /></td>
  29.               <td valign="top" width="<?php echo $percentage2; ?>%"></td>
  30.             </tr>
  31.           </table>
  32.           </td>
  33.           <td valign="top"><?php echo $responses['total']; ?></td>
  34.         </tr>
  35.       <?php
  36.       }
  37.       ?>
  38.       <tr>
  39.         <td valign="top" colspan="3" align="center">Total Votes: <?php echo $total; ?></td>
  40.       </tr>
  41.     </table>
  42.     </td>
  43.   </tr>
  44.   <?php
  45.     }
  46.   ?>
  47. </table>
  48. <?php

Correct! Lots of stuff to sift through. Most of it is HTML. So don't stress. I will run through the code with you now.

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  1. 17 Responses to “Tutorial: How to build a poll system with PHP and mySQL”

  2. By Cristi ROMANIA Windows XP Mozilla Firefox 2.0.0.14 on Jun 11, 2008

    It would be perfect if it had a form to add the question and a form to edit them. Anyway Good Job.

  3. By VoiDeT AUSTRALIA Mac OS X Safari 525.20 on Jun 11, 2008

    Yep sure.
    You should take the guestbook tutorial and build that feature yourself! It is not hard at all

  4. By chor khee SINGAPORE Windows XP Internet Explorer 7.0 on Jul 16, 2008

    nice one man! just a simple question. Can this be done using jsp and mYsql? are there any links for that?

  5. By VoiDeT AUSTRALIA Mac OS X Safari 525.20.1 on Jul 16, 2008

    Hey Chor Khee,

    I don’t know JSP, sorry.
    Have fun with the port!

  6. By Ana Windows XP Internet Explorer 7.0 on Jul 25, 2008

    Thank you very much it really is great, it gave me the whole picture. I am using Access data base, how can I use this nice piece of code for Access. Thanks again.

  7. By Hunter UNITED STATES Windows Vista Mozilla Firefox 3.0.1 on Aug 11, 2008

    Hi,

    I downloaded the source, and uploaded it in tact, minus editing in my database information.

    I get this error:

    http://www.nineprinces.org/hunter/php/tutorials/

    ”
    Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/backline/public_html/hunter/php/tutorials/poll.php on line 4″

    What’s up w/ that? :(

  8. By Hunter UNITED STATES Windows Vista Mozilla Firefox 3.0.1 on Aug 11, 2008

    Nm, fixed it ;)

  9. By VoiDeT AUSTRALIA Mac OS X Safari 525.20.1 on Aug 11, 2008

    And how did you fix it?

  10. By Hanayo UNITED STATES Mac OS X Mozilla Firefox 3.0.1 on Sep 24, 2008

    I tried working on it but I as totally lost when it came to the whole phpmyAdmin thing??

    I couldn’t figure out what you were talking about the click Insert or whatever since I didn’t see that anywhere on my page…

    Like I know how to read html/css fairly well and can read xhtml. But php is what I’m learning, and so i know i put the codes in all the right spots but I don’t know what you meant by that and I tried but I dont’ think i got it…

    http://www.aestheticloveinc.com/poll/index.php and it’s just blank….

  11. By blckheart Windows XP Mozilla Firefox 2.0.0.17 on Sep 25, 2008

    RE: And how did you fix it? Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in

    To fix the error, you will have to connect to the database. In the downloaded files there is no config.php file or db.inc file to connect to the database, therefore the mysql_num_rows cannot find any info from the database, because there is no connection to the database. Or at least this is what happened in my case.

    To connect to the database use the following code in the poll.php file or create a seperate config.php file and just use an include ‘config.php’; or require ‘config.php’; in the top of your poll.php file

    //Connection to Database
    $hostName = “localhost”;
    $databaseName = “yourdatabasename”;
    $databaseusername = “yourdbusername”;
    $dbpassword = “yourdbpassword”;

    $connect = @mysql_connect($host, $yourdbusername, $yourdbpassword);
    if (!mysql_select_db($databaseName, $connect))
    echo ‘Could not connect to database’;

    I hope this helps, i dont know why someone would ask for help on the error and then say he fixed it without giving a solution, he has the time to ask but not the time to help, i think that sucks!

  12. By VoiDeT AUSTRALIA Mac OS X Safari 525.20.1 on Sep 27, 2008

    blckheart what do you think is sitting in the root folder? would it be a config.php file by anychance? With this code in it?

    < ?php

    //database settings

    $hostname = 'localhost';
    $username = 'yourusername';
    $password = 'yourpassword';
    $dbname = 'poll';

    $connect = mysql_connect($hostname, $username, $password);
    mysql_select_db($dbname);

    ?>

    Look at the files.

  13. By BlueDevil18 UNITED STATES Windows XP Internet Explorer 7.0 on Sep 28, 2008

    I set everyhing up. Added a New Poll and Questions to the poll with the correct pid. However, when I browse to the file(poll.php) on the server, it still comes up “No Poll Yet” Am I not doing something?

  14. By BlueDevil18 UNITED STATES Windows XP Internet Explorer 7.0 on Sep 28, 2008

    I need some help with this. I think i set up up correctly, but i still get “no poll yet”

  15. By Rkrueger UNITED STATES Windows XP Google Chrome 0.2.149.30 on Oct 12, 2008

    hey i was doing this and it came up with the error that the function “max()” doesn’t have enough parameters..
    can someone check this out?

  16. By Hodde DENMARK Windows XP Mozilla Firefox 3.0.3 on Oct 28, 2008

    I get the “no poll yet”-message too.. and i’m also pretty sure i set the poll up correctly..

  17. By Stonedeft PHILIPPINES Windows XP Safari 525.17 on Dec 13, 2008

    You should have separated codes and html. It gets real confusing I have to strip html tags the poll.php for me to review the code.

    Well I got the idea but man you should recode this to for web 2.0 standards

  18. By VoiDeT CANADA Mac OS X Safari 525.27.1 on Dec 13, 2008

    Thank you for the comment,
    Web 2.0 standards in php LOL :D Maybe you could say something like, maybe you should use objects, or logic from design separation, but web 2.0 standards haha

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