User manual

Chapter 3 | Creating databases 51
4. After you’ve identified your categories of information, you are ready to organize your database.
In database terminology, these categories of information are referred to as tables. Tables are
used to group data containing a common element or purpose. For example, you might use one
table to store names and addresses, while you use another table to store transaction details,
such as date of sale, item number, unit price, and so on.
Typically, databases are organized in one of three ways:
1 A single table in a single file. Use a single table if you need to track data in one category only,
such as names and addresses.
1 Multiple tables in a single file. Use multiple tables if your data is more complex, such as
students, classes, and grades.
1 Multiple tables in multiple files. Use multiple files if you need to share the same data among
several different database solutions. For example, you can store your tax rates or shipping
information in a separate file if you plan to use that information in more than one solution.
Note Use relationships to share data between tables in the same file or with tables in external
files. Other database elements, such as scripts and access privileges, are stored at the file
level; therefore, some complex solutions will benefit from using multiple files.
5. Determine the database tables and the data they will include, and, in turn, which fields you will need.
Tip To make it easy to search and sort records, create separate fields for first and last name,
titles, (like Mr. or Dr.), and items in addresses (city, state or province, country, and postal code).
Separating your data into multiple fields at the time of data entry can make it easier to generate
future reports. For example, using separate fields to capture transaction details such as the
date, item number, quantity, and unit price of each transaction makes it easier to compile
summary and subsummary reports at the end of a week, month, or year.
6. Decide which fields will contain common data among the tables.
For example, a database for a bakery business might include these tables: a Customers table,
which stores customer information; a Products table, which stores product information; and an
Invoices table, which stores order information.
Each table has only one subject, and all fields in a table describe only that subject. For example,
the fields in one record of the Customers table together store all the information about one
customer. For the same reason, you might assign each customer a unique, identifying number.
You wouldn’t enter a customer identification number into the table unless you had a new
customer to add, so the existence of a customer number determines the existence of a record.
A Customers table might also have fields for the customer’s name, address and phone number.