Information system : Introduction to MERISE and MCD

Information system : Introduction to MERISE and MCD

 1. The information system:

 The information system or IS can be defined as the set of human, material and immaterial means used to manage information within a unit, such as a company.

Information system to manage informations

However, an information system should not be confused with a computer system. Indeed, information systems are not always fully computerized and already existed before the arrival of new information and communication technologies, of which information technology is an integral part.

The IS has 4 essential functions:

* The capture or collection of information.
* Storing information using a file or database. 
* The processing of information in order to better exploit it (consultation, organization, updating, calculations to obtain new data, ...). 
* Dissemination of information.

Formerly, information was stored on paper using forms, records, ... and there were manual procedures to deal with it. Today, computerized systems, such as relational database management systems (RDBMS), are used by the information system.

2. MERISE:

 

MERISE is a French method born in the 70s, initially developed by Hubert Tardieu. It was then promoted in the 1980s at the request of the Ministry of Industry, which wanted an IS design method.

Merise method effective

MERISE is an IS analysis and design method based on the principle of separation of data and processing. It has a number of models (or diagrams) that are spread over 3 levels:

    *  The conceptual level,
    * The logical or organizational level,
    * The physical level.

In this course, we will be interested only in certain schemas allowing the design of a relational database and then its realization on a RDBMS.

3. Conceptual Data Mode :

This is the development of the Conceptual Data Model (MCD in french), which is a graphical and structured representation of the information stored by an IS. The MCD is based on two main notions: entities and associations, hence its second name: the Entity / Association scheme.

The development of the MCD involves the following steps:

    *  The implementation of management rules (if these are not given to you),
    *  The development of the data dictionary,
    * The search for functional dependencies between these data,
    * The development of the MCD (creation of entities then associations and addition of cardinalities).

 

How to create comments system using PHP and MYSQL

Hello Programmers this is my first lesson in PHP and it talk about how to make and create system comments to your website or any websites you want. All forums use this system and the most of websites.

create comment system by using PHP and Mysql @wikihard

I wish you take advantage of the lesson and learn more about PHP programming.

Notice : All big websites use COMMENTS SYSTEM like Facebook, Twiter and google plus.

Facebook Example :

Simple System comments of the Facebook @wikihard

Google+ plus Example :

Google plus comment @wikihard

Google and Facebook are using Javascript, but in this topic I will show you how to create a simple system commenst by using PHP & MYSQL only, I need you to learn the basic, then you can improve it yourself!

firstly you must to create a php file called connect.php and put the script bellow in, This file will help us to manipulate between the website and database without any problem.

  Connect.php File :

<?php

$user='username';

$user='username'; 

$pass='password'; //@wikihard copywrite

$host='localhost'; // if you have a web hosting change this infos


$database='public';

mysql_connect("$host", "$user", "$pass")or die("cannot connect");

mysql_select_db("$database")or die("cannot select DB");


?>

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When you finish connect.php file, we will start to create new important file called index.php, we will use this page to display our comments and to add more comments too.

<?php

require_once('connect.php');
$message ='';
if(isset($_POST['submit']))
{
if(!empty($_POST['comment']) && !empty($_POST['name']))
{

//created by @wikihard
$comment= $_POST['comment'];
$name= $_POST['name'];
$query = "INSERT INTO `comment` VALUES(NULL,'$name','$comment')";
$qresult = mysql_query($query);
$message="Thank you for comment!";

} else
{
$message="please don't let area empty!";
}

}

$sql = "SELECT * FROM `comment`";
$qsql = mysql_query($sql);




?>
<!DOCTYPE html>
<body>
<?php
while ($row = mysql_fetch_array($qsql))
{
echo "<b>".$row['name']."</b> : </br>";
echo " ".$row['comment'].". </br></br>";
?>
<form method="post" action="index.php">
<input type="text" name="name" placeholder="put your name"></br></br>
<textarea rows="5" cols="25" name="comment" placeholder="write your comment here"></textarea></br></br>
<input type="submit" name="submit" value="post comment">
</form>
<?php echo $message;?>
</body>
</html>

 How it work :

- First we must call the connect.php file to connect with the database!

- When we add value and press the button "Add comment", the comment will send and save in the comments table(id,name,comment) in the database.

- if the fields are empty, will NOT WORK and this message will show for the user "please don't let area empty " Until he put values before submitting.

- Now we need to display all comments from the database (comments table) to the home page ( index.php ).

Any question please let a comment! Good luck