---
description: In this PHP project, we are going to create an opinion poll application. The opinion poll will consist of 3 major components; Front controller, Business Logic, View.
title: PHP Projects: Create an Opinion Poll Application
image: https://www.guru99.com/images/case-study-opinion.png
---
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In this PHP project**,** we are going to create an opinion poll application.
The opinion poll will consist of 3 major components;
**Front controller** – this is the index page that will determine the HTML code to be loaded. This will ensure that our application has a single entry point. This will give us more control over the application.
**Business Logic** – this will contain the PHP code for interacting with the database. This will allow us to separate the business logic from the presentation making our application easy to maintain
**Views** – this will contain the HTML code. We will have two pages namely;
* opinion.html.php – this will contain the HTML code with the question and options
* results.html.php – this will contain the HTML code that displays the opinion poll results
Assumptions made
The opinion poll will ask the question –
What is your favorite[ JavaScript ](https://www.guru99.com/interactive-javascript-tutorials.html)Library?
Answers would be
* JQuery
* MooTools
* YUI Library
* Glow
Here are the steps to create the application–
## Step 1) Database Connectivity
This section assumes knowledge of MySQL and how to administer it, if you are not familiar with these MySQL, check our [SQL tutorials](https://www.guru99.com/sql.html) section.
Our application will have one table only with 3 fields namely;
* id – auto-generate number as the primary key
* choice – the number representing a presidential candidate
* ts – the timestamp for the vote
The script below creates our js\_libraries table.
## Step 2) Coding our application
Let’s now create our business logic layer that will handle the database connectivity. _‘opinion\_poll\_model.php’_
db_handle = mysqli_connect($this->host, $this->uid, $this->pwd); //connect to MySQL server
if (!$this->db_handle) die("Unable to connect to MySQL: " . mysqli_error());
if (!mysqli_select_db($this->db_handle,$this->db)) die("Unable to select database: " . mysqli_error());
}
private function execute_query($sql_stmt) {
$result = mysqli_query($db_handle,$sql_stmt); //execute SQL statement
return !$result ? FALSE : TRUE;
}
public function select($sql_stmt) {
$result = mysqli_query($db_handle,$sql_stmt);
if (!$result) die("Database access failed: " . mysqli_error());
$rows = mysqli_num_rows($result);
$data = array();
if ($rows) {
while ($row = mysqli_fetch_array($result)) {
$data = $row;
}
}
return $data;
}
public function insert($sql_stmt) {
return $this->execute_query($sql_stmt);
}
public function __destruct(){
mysqli_close($this->db_handle);
}
}
?>
HERE,
* “public function \_\_construct()” is the class constructor method that is used to establish the database connection
* “public function execute\_query(…)” is the method for executing queries such as insert, update and delete
* “public function select” is the method for retrieving data from the [database](https://www.guru99.com/introduction-to-database-sql.html) and returning a numeric array.
* “public function insert(…)” is the insert method that calls the execute\_query method.
* “public function \_\_destruct()” is the class destructor that closes the database connection.
Let’s now create the front controller _index.php_
alert('You did not vote!');";
}
if (count($_POST) > 1) {
$ts = date("Y-m-d H:i:s");
$option = $_POST['vote'][0];
$sql_stmt = "INSERT INTO js_libraries (`choice`,`ts`) VALUES ($option,'$ts')";
$model->insert($sql_stmt);
$sql_stmt = "SELECT COUNT(choice) choices_count FROM js_libraries;";
$choices_count = $model->select($sql_stmt);
$libraries = array("", "JQuery", "MooTools", "YUI Library", "Glow");
$table_rows = '';
for ($i = 1; $i < 5; $i++) {
$sql_stmt = "SELECT COUNT(choice) choices_count FROM js_libraries WHERE choice = $i;";
$result = $model->select($sql_stmt);
$table_rows .= "| " . $ libraries [$i] . " Got: | " . $result[0] . " votes |
";
}
require 'results.html.php';
exit;
}
require 'opinion.html.php';
?>
HERE,
* “require ‘opinion\_poll\_model.php’;” loads the business logic class
* “$model = new Opinion\_poll\_model();” creates an instance of the business logic class
* “if (count($\_POST) == 1)…” performs the data validation and uses JavaScript to display a message box if not candidate has been voted for.
* “if (count($\_POST) > 1)…” checks if a vote has been selected by counting the number of items in the $\_POST array. If no item has been select, the $\_POST will only contain the submit item. If a candidate has been chosen, the $\_POST array will two elements, the submit and vote item. This code is also used to insert a new vote record and then display the results page
* “exit;” is used to terminate the script execution after the results have been displayed so that the opinion poll form is not displayed.
* “require ‘opinion.html.php’;” displays the opinion poll form if nothing has been selected.
Let’s now create the views. _opinion.html.php_
JavaScript Libraries - Opinion Poll
JavaScript Libraries - Opinion Poll
What is your favorite JavaScript?
_results.html.php_
JavaScript Libraries Poll Results
Opinion Poll Results
What is your favorite JavaScript Library?
people have thus far taken part in this poll:
## Step 3) Testing our application
Assuming you have saved the files in opinionpoll folder, browse to the URL http://localhost/opinionpoll/
[](https://www.guru99.com/images/2013/04/opinion%5Fpoll%5Fhome.jpg)
If you click on the Ok button without selecting a JS library, you will get the following message box.
[](https://www.guru99.com/images/2013/04/validation%5Fmsg.jpg)
Select a JS library then click on OK button. You will get the results page similar to the one shown below.
[](https://www.guru99.com/images/2013/04/opinion%5Fpoll%5Fresults.jpg)
## Summary
* Dividing your application into business logic, front controller view layers is a good application design practice
* JavaScript is useful for performing client-side validation
* It is a good programming practice to use file.html.php for files that contain both HTML and [PHP codes](https://www.guru99.com/php-tutorials.html)
* The opinion poll application demonstrates how the knowledge learned in the previous lessons can be put together to developing a working application with a database back end.
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