Following is an example of the use of attributes and entities for the
representation of the real world: consider the address of a person. Is
it an entity, relationship, or attribute?
- Consider address for a telephone company database, which has to keep
track of how many and what type of phones are available in any one household,
who lives there (there may be several phone bills going to the same
address) etc. for this case, address is probably best treated as an
- Or, consider an employee database, where for each employee
you maintain personal information, such as her address.
Here address is best represented as an attribute.
- Or, consider a police database where we want to keep track of a person’s
where-abouts, including her address (i.e., address from Date1 to Date2,
address from Date2 to Date3, etc.) Here, address is treated best as
Ontologies are used in our everyday lives, although most of us do not
realize it. An example of how this happens follows:
- The department name
- The year in of academic studies in which the course is taught
- The subject area
- And the course number