Access methods return the value of an attribute or set of attributes of a class instance. It may return a single attribute value, multiple attribute values, or a collection of values. For example, we may have a method getSalary for a class SalesStaff that returns a member of staff’s salary, or we may have a method getContactDetails for a class Person that returns a person’s address and telephone number. An access method may also return data relating to the class. For example, we may have a method getAverageSalary for a class SalesStaff that calculates the average salary of all sales staff. An access method may also derive data from an attribute. For example, we may have a method getAge for Person that calculates a person’s age from the date of birth. Some systems automatically generate a method to access each attribute. This is the approach taken in the SQL:2003 standard, which provides an auto- matic observer (get) method for each attribute of each new data type (see Section 28.4).