Monday, May 26, 2008

Creating a Simple Poll Script in PHP

OK, so again a useful script that we are going to create here. A polling system/script needs no introduction as it has been on the Web since long and is a good method to increase visitor activity on a website, apart from knowing their responses.

OK let’s start!

A polling system requires vote data to be stored, for that database (MySQL) would be the best choice.

Possible table structure for the database for a poll having three options would be

Logically thinking we know that only one row is required for a poll. Each time someone votes the value of the respective fields should be updated (incremented).

Initially the table would be like below:

Initial values in the table

After five votes to the first option, four to the second option and one to the third; the table would look like:

Values in the DB table after some votes

It should now be clear why we only need one row for a poll.

Designing the Poll

OK, now we’ll have to design the poll using an HTML table, some radio buttons and a submit button. You may write your poll question and the options besides the radio buttons. We’ll now have to integrate this to the script.

A sample Poll created by me:

A sample poll craeted by me

[NOTE: Radio boxes gives us the ability to let the visitor select ONLY ONE option from many.]

The Script

We are going to create the script such that it shows the Poll (HTML form) when no $_GET data is being passed, in other words visitor is requesting the Poll. It acts accordingly when someone is tries to see the results or vote their choice. After successful voting the result page is shown.

Here is the completed script:

<title>Polling System</title>

<h1>My Poll</h1>
//connect to MySQL 
//provide your 'USERNAME' and 'PASSWORD' 
//change 'localhost' to the MySQL server 
//host, if MySQL is on a sepearte server 
$db=new mysqli('localhost','-USER-','-PASS-');

//if this is the first time
//and database is not craeted
//create the database
$db->query('create database one');
//select the databasw to work with
//if table is not created, create it
if(!$db->query('select * from poll'))
//create a table for a Poll having three options
$db->query('create table poll (id int auto_increment primary key, option1 int, option2 int, option3 int)');
//create an initail row with value of 0 to each field
$db->query("insert into poll (option1, option2, option3) values (0,0,0)");

//someone is trying to vote
//--you may add more if needed
    //be sure to add same no. of radio buttons 
    //on the form too.
    //if any option was selected, then only save the vote
if($option1!='' || $option2!='' || $option3!='')
//fetch initial values of polls in DB
$result=$db->query("select * from poll");

//increment the voted option
//save the updated values
$db->query("update poll set option1='$op1', option2='$op2', option3='$op3'");
//redirect to results page
        //by setting the $_GET var
//fetch initial values of polls in DB
$result=$db->query("select * from poll");

//close DB
//using HTML with embedded PHP for ease
    <h3>Poll Results</h3>
    <p>How does it feel to be able to vote to your own Script?</p>
     <p>Very Good!: <?php echo $op1?></p>
     <p>Not Bad...: <?php echo $op2?></p>
     <p> Bad...: <?php echo $op3?></p>

//closing of PHP blocks may be done this way
//show poll form
    <h3>Cast Your Vote</h3>
    <form name="form1" id="form1" method="get" action="">
      <p>How does it feel to be able to vote to your own Script?</p>
    <input type="radio" name="option1" value="voted" />
        Very Good!</p>
        <input type="radio" name="option2" value="voted" />
        Not Bad...</p>
        <input type="radio" name="option3" value="voted" />
        <input name="action" type="submit" id="action" value="Vote" />
    <p><a href="?action=Results">Show Results</a></p>

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1 comment:

  1. hi,
    i am getting these error please help

    Notice: Undefined index: action in C:\wamp\www\MySQL\mynewpoll.php on line 34
    Notice: Undefined index: action in C:\wamp\www\MySQL\mynewpoll.php on line 68
    Notice: Undefined index: option1 in C:\wamp\www\MySQL\mynewpoll.php on line 36
    Notice: Undefined index: option2 in C:\wamp\www\MySQL\mynewpoll.php on line 37
    Notice: Undefined index: option3 in C:\wamp\www\MySQL\mynewpoll.php on line 38


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