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

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

At this point you will have a working poll system. But what if you want to add your own questions and make new polls? Simple. All you need to do is edit the contents of the database in two places.

8. Firstly open up phpmyadmin. Then click on the database you made and then on the table name poll. Here is where all your polls are stored. Click on the button Insert. Simply make a title for your poll and click go. Next click browse. You will see your entry there, along with an id number. Remember this id number and click on the table name questions.

Do the same with insert, however type in the poll id (pid) which is the number you just remembered, and then the question title. Repeat this process with the question titles and the same pollid until you have all the possible responses you want!

And thats it! You have now set up a new poll. Remember at the start of the tutorial we said we would only show the newest poll, well since your new poll has a greater id number than the previous, it is considered the newest now.

*UPDATE*
The poll bars did not extend to the entire width of the area, that is because we were using strict percentages, in comparison to the total amount of votes. In order to make the bars extend to the full width, and in doing so making the option with the most votes equal 100% we must compare all other votes with that of the most voted option. So to do so open up poll.php and:

After:

if($rows > 0){
		$poll = mysql_fetch_array($query);
		$title = $poll['name'];
	} else {
		$title = 'No Poll Yet';
	}

Add:

$query = mysql_query("SELECT COUNT(`id`) as hits FROM `responses` GROUP BY `qid`");
	while($row = mysql_fetch_array($query)){
		$me[] = $row['hits'];
	}
	$max = max($me);

Next Find:

$percentage = round(($responses['total'] / $total) * 100);

And replace with:

$percentage = round(($responses['total'] / $max) * 100);

Also another update to fix division by zero:
Find:

$percentage = round(($responses['total'] / $max) * 100);

Replace with:

if($total > 0 && $responses['total'] > 0){
						$percentage = round(($responses['total'] / $max) * 100);
					} else {
						$percentage = 0;
					}

Done! Now your bars are constructed in comparison to the most popular option!

Posted by VoiDeT

Categorised under PHP
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70 Comments

  1. voidet. Of course! Sent you some cash and put a link in.
    Many thanks for your hard work!

    July 31, 2009 @ 12:03 am
  2. VoiDeT

    Hey!
    Thanks alot for the donation!
    I really appreciate that! If people are using the tutorial as a learning tool i’m all for it, we both can build something up that way. But if people are going to use it for their own web apps, it’s not right to just take and not give anything back :)

    But thanks alot for the donation! I am glad it worked out for you :D
    Also if you need any future help with anything just let me know!

    July 31, 2009 @ 10:29 am
  3. Honestly it was a learning tool for me. And I ended up using it successfully which I thought was very cool.
    I am happy to give back and may call on you again. Thanks very much.

    July 31, 2009 @ 10:57 am
  4. VoiDeT

    Hey Artech!

    Really cool portfolio you have!
    Love the graphics!

    July 31, 2009 @ 11:41 am
  5. Artech

    Thanks Voidet.
    I enjoy working with flash. Creating with graphics in mind is usually how I approach things. But I’m getting more and more into the scripting side of things. Really appreciating the functionality and management.

    July 31, 2009 @ 1:48 pm
  6. VoiDeT

    You should get into the frameworks!
    Just jump into CakePHP :D

    July 31, 2009 @ 2:02 pm
  7. frank

    will this code work if i want to ask a series of independant yes or no question that i want to rate separately?

    August 24, 2009 @ 11:57 pm
  8. VoiDeT

    This is a poll script.
    To turn it into a survey type program would require some refactoring.
    Not too much if you want it hardcoded, but alot if you want it to be dynamic :)

    August 24, 2009 @ 11:59 pm
  9. Hi, great tutorial, thanks man. :D

    August 25, 2009 @ 4:10 am
  10. iz

    hi, anyone know how we get the value of $responses['total'] hmm i starter in php wondering where we get the ‘total’ from? thx for any help..

    August 27, 2009 @ 11:42 am
  11. VoiDeT

    IZ please clarify here!
    Do an echo $responses['total'] to output the total number of responses!

    August 27, 2009 @ 11:54 pm
  12. Diogo

    Really good tutorial!! THX!! I’m just modifying a bit to fit on my page and to my taste.

    But again, thx, i learned a lot here!

    October 14, 2009 @ 8:42 am
  13. Hi.. nice tutoria! i have a question

    Warning: Wrong parameter count for max() in C:\wamp\www\poll\poll.php on line 17

    what does it mean? and how can i solve it? thanks…

    January 11, 2010 @ 3:33 pm
  14. VoiDeT

    Hey Ralph,

    Below “$query = mysql_query(“SELECT COUNT(`id`) as hits FROM `responses` GROUP BY `qid`”);”
    Add:

    $me = array();

    January 15, 2010 @ 9:22 am
  15. Ralph

    thanks VoiDeT.. ill try it! ^__^

    January 21, 2010 @ 12:19 am
  16. shaeeb

    Hi, followed your tutorial, this is for personal learning.. im new to PHP. was a great tutorial even for those who don’t code all the time. I just had 2 questions, everything is up and working, but my main page is also called index.php, if i change the name of the index.php that you set as default would it still work fine?

    also, how do i add more polls? i want to add atleast three or four questions, thanks.

    March 23, 2010 @ 2:00 am
  17. VoiDeT

    Try changing the name and see what happens.
    There might be references to index.php in the code, or it could just be SELF. I forget a lot of the code in this, as this desperately needs a re-write.
    If you want to add more polls or questions you should do so in the database. However you will need to cycle through the polls somehow.

    Thanks,
    Richard

    March 23, 2010 @ 8:49 am
  18. Shaeeb

    Thanks, I will try changing the name and see what happens, I basically want to have 3-4 polls running at the same time, if I cant sort it out I will have to stick to one poll

    March 23, 2010 @ 11:10 pm
  19. Richard

    Hi Voidet,

    I clicked on the link you give above but it seems to be malfunctioning…http://www.jotlab.com/tutorials/poll/index.php
    ++++++++++++++++++++++++++++++++++++++++++++++++Warning: mysql_connect() [function.mysql-connect]: Access denied for user ‘voidet_jotlab’@'localhost’ (using password: YES) in /var/www/jotlab.com/public_html/tutorials/poll/config.php on line 10

    Warning: mysql_select_db() [function.mysql-select-db]: Access denied for user ‘www-data’@'localhost’ (using password: NO) in /var/www/jotlab.com/public_html/tutorials/poll/config.php on line 11

    Warning: mysql_select_db() [function.mysql-select-db]: A link to the server could not be established in /var/www/jotlab.com/public_html/tutorials/poll/config.php on line 11

    Warning: mysql_query() [function.mysql-query]: Access denied for user ‘www-data’@'localhost’ (using password: NO) in /var/www/jotlab.com/public_html/tutorials/poll/poll.php on line 3

    Warning: mysql_query() [function.mysql-query]: A link to the server could not be established in /var/www/jotlab.com/public_html/tutorials/poll/poll.php on line 3

    Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /var/www/jotlab.com/public_html/tutorials/poll/poll.php on line 4

    Warning: mysql_query() [function.mysql-query]: Access denied for user ‘www-data’@'localhost’ (using password: NO) in /var/www/jotlab.com/public_html/tutorials/poll/poll.php on line 13

    Warning: mysql_query() [function.mysql-query]: A link to the server could not be established in /var/www/jotlab.com/public_html/tutorials/poll/poll.php on line 13

    Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /var/www/jotlab.com/public_html/tutorials/poll/poll.php on line 14

    Warning: Wrong parameter count for max() in /var/www/jotlab.com/public_html/tutorials/poll/poll.php on line 17

    Warning: mysql_query() [function.mysql-query]: Access denied for user ‘www-data’@'localhost’ (using password: NO) in /var/www/jotlab.com/public_html/tutorials/poll/poll.php on line 19

    Warning: mysql_query() [function.mysql-query]: A link to the server could not be established in /var/www/jotlab.com/public_html/tutorials/poll/poll.php on line 19

    Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /var/www/jotlab.com/public_html/tutorials/poll/poll.php on line 21

    Warning: mysql_query() [function.mysql-query]: Access denied for user ‘www-data’@'localhost’ (using password: NO) in /var/www/jotlab.com/public_html/tutorials/poll/poll.php on line 77

    Warning: mysql_query() [function.mysql-query]: A link to the server could not be established in /var/www/jotlab.com/public_html/tutorials/poll/poll.php on line 77

    Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /var/www/jotlab.com/public_html/tutorials/poll/poll.php on line 78
    ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    any help is always appreciated
    rca08207 at bigpond dot net dot au

    April 6, 2010 @ 5:30 pm
  20. A very detailed and helpful tutorial indeed. Loved it. I made a collection of all such tutorials and scripts (including this one) at 11 PHP Voting Scripts and Tutorials. I hope it would be helpful to many. :-)

    June 13, 2010 @ 9:10 pm

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