Business computing Databases 11 January 2005

Importance of Databases Databases are softwares to store, treat and retrieve (and therefore distribute) STRUCTURED information in the business world They are all over the place in the business world Databases are more complicated to deal with than Word, Excel or PowerPoint

Databases and websites Mail order companies make a heavy use of databases –To manage their client database –To manage their website Go to We see a website using a database to construct the pages on demand

Dynamic links in Office When in a Word letter we display a table coming from Excel with a dynamic link, we actually implement an action very close to calling a database Remember that in business we work mostly with INFORMATION, and when possible with STRUCTURED INFORMATION The value added of managers is mostly value added on information, since managers do not manufacture any product.

Creation of a simple database on Excel An Excel table is the equivalent to a simple – one table – database Each row is a record And the fields of each record correspond to the columns Such a table can be IMPORTED into Access

The problem of redundant data The simple database obtained from importing the Excel sheet presenting data on 10 people has some redundancy. Each record (that is person) working at Futuroscope bears the address of Futuroscope This is waste of space, and a risk of mistakes when we enter new records The employer’s information should go into a separate table

Access and redundant data Access has a tool that allows us to analyse and split one table into several tables, in the case where data are redundant. The new architecture of the database is more sturdy, and less prone to entering mistakes

The three types of work with a database 1.Store data: 1.Define the architecture of tables 2.Enter the data 2.Make some treatment on the data 3.Ask question to the database (retrieve information and display it) 1.« who are the people who work at Futuroscope and live in Paris ? » 2.« What were the sales of drinks, in 2004, and 2003, in Asia ? » (Is there a progress ?)

Simplest requests A database central function is to answer quickly questions on a large body of structured data The simplest requests are called « filtering » (two slightly different varieties): –Filtering by selection –Filtering by form Filtering works only on one table at a time Requests can be designed taking advantage of the multitable architecture.

Where is the data ? When beginning working with a database, once in a while we have the natural question : « But where is the data ? » Answer : the data is stored into several tables. Often we never go into these TABLES We display data using FORMS And we interrogate our database using REQUESTS

Displaying data We display the data contained in a database using FORMS The forms we create and use are at our choice They rarely display the entire data When the database is big, we never view or display the entire data Let’s create a form with the database of our 10 people

bdcomptoir.mdb bdcomptoir.mdb is an 8-table-database with 2155 elementary pieces of information (stored into the 8 tables) that records sales information over several years of a food wholesaler It can be found at lesson 9 Now we are ready to understand the structure and the usefulness of this database (a large database is called « an information system »)

Teaching progression 1.A list of 10 people, with some attached information, stored into Excel 2.Excel as a simple database 3.Creation of an Access database into which we imported the Excel sheet 4.Same database functions 5.The Access database can be reorganised into a better architecture : analysis -> 3 tables ; avoids mistakes in entering more data 6.Display of information about the 10 people, into various forms

Teaching progression (2) 7.bdcomptoir.mdb : information about 830 orders, over 3 years, into 8 tables 8.We can display information into forms of our choice 9.We can make request like this : « What turnover did we make with the product « Guarana Fantastica » ? », « In how many orders ? », « What other products are usually ordered with it ? »…