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 http://www.camif.fr

• 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 http://www.lapasserelle.com/escem/business_computing 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 database3. Creation of an Access database into which we

imported the Excel sheet4. Same database functions5. 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 ? »…