Encapsulation, or "They've hidden my data"

Let's assume we've got a relational table for employees⁹⁵, and it's got columns such as Employee No for the employee's number, and Employee Name for their name. We've also got a Date-Of-Birth column, and we want to be able to compute their "age". Using UML notation, where the "age" column name is preceded by a slash ("/") to indicate it is derivable, we might represent this "table" as follows, where the name of the table is in the first internal rectangle, and the list of columns is in the second internal rectangle:

Figure 53. UML – derivable attribute