Built-in databases
The Palm handheld actually is manufactured with some built-in, special purpose databases. One is the Address Book, and the other is the To Do application. These special purpose databases are limited in what the fields are named, which fields we can sort on, and which fields we can filter on. And when we do a Find, every field in the database is searched, and we're not able to choose between finding 123 in a telephone number field versus 123 in an address field. The only sorting allowed is either by Last Name or Company. The only filtering permitted is by Category. There are four Custom Fields that can be renamed, and the five telephone number fields can be relabeled. These restrictions limit the flexibility. I'm not criticizing the Palm Address Book application-which is an excellent application for what it was designed to do-but giving an example of a specific, rather than a general purpose, database.

Three types of databases
You'll find many third-party databases on the Internet that will run on the particular database program you have chosen to use. I've defined three variations of databases: static, dynamic, and templates.

Static databases
The static databases that you can build or download from the Internet contain data that doesn't change very often or at all. The States Information database is one such collection. It contains 50 records, one for each state in the U.S. The data is fairly static, such as state flower or state bird. The population will change every ten years after a census, but that's probably the only field that will change over time. Normally you can set this type of database to read-only, which means you can't accidentally add, delete, or modify any records. The read-only property is a mild protection against alteration. If you do want to change a record, turn the read-only property off, make your change, and turn it back on again.

Dynamic databases
Dynamic databases are constantly changing. Most of the time you'll add new records, such as an expense database. You might also delete old records and perhaps modify a record when necessary. You usually wouldn't download a dynamic database with data in it, but there are some instances where you would. For example, I downloaded an Area Code database with current area code, city, and state fields already entered. But I have to periodically add new records as new area codes are assigned. Normally I set the read-only property on my area code database so I don't accidentally change any data.

Template database
What you most likely would download from the Internet is a template for a dynamic database. Most database software developers have some pre-defined templates on their sites and links to locations where you can find more. A template is an empty database before any records have been added. If you download an expense database, you don't want someone else's data in it, do you? Most database programs have the capability of deleting all records. So if you have a favorite database design and you want to beam it to a friend, make a copy and delete all of your personal records from the copy. Then beam the empty template to your friend.