User Guide

450 Chapter 19: Introduction to Databases and SQL
d
In this example, each table contains a column named EmpID. This column associates a row of
the employees table with a row in the addresses table.
For example, to obtain all information about an employee, you request a row from the employees
table and the row from the addresses table with the same value for EmpID.
One advantage of using multiple tables is that you can add tables containing new information
without modifying the structure of your existing tables. For example, to add payroll information,
you add a new table to the database where the first column contains the employee’s ID and the
columns contain current salary, previous salary, bonus payment, and 401(k) percent.