Definition of information and information systems
Information is an element which makes it possible to complete our knowledge of a person, an object, an event, etc.
- A person's name is information about that person.
- The color of a car is information about this car.
- The date of the school holiday is information concerning this event.
An information system is made up of all the information relating to a well-defined area.
- All the information relating to the management of a library constitutes the information system of this library. This system can cover the simple storage of books, but also the management of orders, sales and even customers.
An information system does not necessarily have to be computerized. Although most of today's systems are based on computer technology, there are still information systems where information is stored, manipulated and communicated using "traditional" means such as cupboards, filing cabinets, calculators, paper charts, etc.
An information system exists independently of computer techniques.
The information system should not be confused with the computer system which consists of the following elements:
- The programs
- Data structures (Files, Databases)
Data, processing and information
Although the two terms "information" and "data" are often used as synonyms, there is a subtle difference between them.
In a bookstore, a customer asks the seller if the book "Introduction to algorithms" (Cormen) is available in stock. The seller check the bookstore database using his computer and confirms to the customer that the book is available. The seller has therefore given the customer the information that the book is in stock. In order to be able to give this information, the seller had to consult the data which represents the stock of the bookshop. The fact of consulting the stock constitutes a processing on the data of the stock.
We can generalize the information system as follow :
An information system contains the data and processing necessary to assimilate and store the incoming information and produce the outgoing information.
In information systems we generally find the following treatments:
- Data consultation;
- Adding data;
- Data deletion;
- Modification of data.
The owner of a video library receives a delivery with new video cassettes. For each video cassette, he(she) reads the title, the language and the duration and saves this information in the database of the video library. He therefore used data addition processing to transform the incoming information (title, language, duration) into data.
Computer representation of data
The data of an information system can be stored and manipulated using a computer tool specialized in this field. Currently Database Management Systems (DBMS) are the most suitable type of software to implement most information systems. Knowing that the tables form the storage base of a database, we can represent any information system by a set of tables, each of which contains a certain number of data fields. We will see that we can even define links between these tables via common fields.