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).

 

Information System - Full definition and objectives

1- What is an Information System?

An information system is a collection of items that collect, process, store and disseminate information in order to assist in the decision-making, coordination and control of a business.

The information system is used by actors (users, administrators, managers) to manipulate (consult, modify, communicate) data using procedures.

INFORMATION SYSTEM - COMPUTER SCIENCES LESSONS - WIKIHARD

 

2-  The information system

The information system contains information about the people, products, customers needed in the organization or in its environment.

Two basic concepts for understanding the information system are data and information.

- Data are raw values, products, orders, purchases, events that take place in or outside organizations. This is in most cases "simple" information associated with a code. If it does not contain this code, the user is unable to understand the information to be transcribed. For example, code 14 means nothing to a user. While in the information system code 14 can represent the number of the client named "Jean Pierre Dupont".

- Information covers data that is presented in a form usable and useful to users. Unlike data, information is something that the user understands (and therefore "usable").

- For example, the address of a customer.

In the information system, the production of the information necessary for the organization consists of three activities.

- Input: arrival of the raw data (input of a user, coming from another system). For example, ordering a customer.

- Data processing: transformation of raw data.

- Output: the process of disseminating information to users who need it. For example, a user consulted look at the stock status.

COMPANY INFORMATION SYSTEM - WIKIHARD

3- The different dimensions of the information system

We can now examine the dimensions of the information system: 

- Organization

- Technology

- Management

Personnel, structure, business processes, policy and culture are the key elements of an organization. Sometimes, the IS is the basic building block of a business. In other words, these companies could not exist without the use of the information system. For example, airlines or companies specializing in online sales.

The operational system will help the players to carry out the basic activities and transactions of the organization (sales, payroll, stock supply, invoicing, etc.). In the airlines, reservations can only be managed with the information system. How do I know how many seats are reserved for a particular flight? What are the names of travelers? Who will be his pilot? In order for each actor to be able to consult the information concerning him, the information system must be able to provide precise elements in a minimum of time. Here, we highlight the place of the information system within companies.

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