Understanding Databases, Fields, and Records

There are hundreds of examples of databases in everyday life. In addition to the phone book, your personal address book is a database. Mailing lists that you rent or buy are also databases. Lists of items you stock in inventory to sell are databases. Each database contains a collection of related information.

In three of the examples I cited, the information in each database is similarname, address, and phone number information. The difference between the databases is the way in which the information is related. In a telephone book, all the entries are of people who live in the same city. Your personal address book contains entries for people you know. Each mailing list shares some common denominator; perhaps the people listed all signed up for a seminar or all purchased a toaster oven.

Identifying the relationship of the information in the database becomes important when you need to find an entry in a database. Because you keep different databases for different purposes, recognizing the relationship of the information in the database will help you search the correct database for the entry. Searching a mailing list of those who purchased toaster ovens for the phone number of your friend in Seattle will not help you find your friend's phone number unless your friend happened to purchase a toaster oven.

In addition to the relationship of the information in the database, a database has an identifiable structure to it. Each entry in the database contains the same type of information. For example, the typical entry in an address book contains, at a minimum, a name, address, and telephone number. Each entry in the address book is, in database parlance, a record. Each piece of information in the entrythe name, the telephone numberis called a field. So, in the terminology of databases, the database is composed of records, and each record is composed of fields.

Databases stored in spreadsheets, such as the one shown in Figure 12.1, make it easy to identify records and fields. In a spreadsheet database, each database record is stored on one row and each column heading represents a field and describes one piece of information that you are storing in the record.

Figure 12.1. In a spreadsheet database, each record appears on a single row, and each field appears in a single column.