Data choosing tips when building database

First, you must identify what information belongs in your database. Look at the list of tasks that you want the application to perform and determine what information you need to complete each of those tasks.
Here are a few examples:

• An online catalog needs a database containing product information. _ An online order application needs a database that can hold customer information and order information.
• A travel Web site needs a database with information on destinations, reservations, fares, schedules, and so on.

In many cases, your application might include a task that collects information from the user. You’ll have to balance your urge to collect all the potentially useful information that you can think of against your users’ reluctance to give out personal information — as well as their avoidance of forms that look too time-consuming. One compromise is to ask for some optional information. Users who don’t mind can enter it, but users who object can leave it blank. Another possibility is to offer an incentive: The longer the form, the stronger the incentive that you’ll need to motivate the user to fill out the form. A user might be willing to fill out a short form to enter a sweepstakes that offers two sneak-preview movie tickets for a prize. But if the form is long and complicated, the prize needs to be more valuable, such as a free trip to California and a tour of a Hollywood movie studio.

In the first example application, your customers search the online catalog for information on pets that they might want to buy. You want customers to see information that will motivate them to buy a pet. The information that you want to have available in the database for the customer to see is as follows:

• The name of the pet (for example, poodle or unicorn)
• A description of the pet
• A picture of the pet
• The cost of the pet

In the second example application, the Members Only section, you want to store information about registered members. The information that you want to store in the database is as follows:

• Member name
• Member address
• Member phone number
• Member fax number
• Member e-mail address

Take the time to develop a comprehensive list of the information you need to store in your database. Although you can change and add information to your database after it’s developed, including the information from the beginning is easier. Also, if you add information to the database later — after it’s in use —the first users in the database will have incomplete information. For example, if you change your form so that it now asks for the user’s age, you won’t have the age for the people who have already filled out the form and are already in the database.