7.3: Attributes

Attributes are the characteristics that describe entities and relationships. For example, a Student entity may be described by attributes including:

    • student number
    • name
    • first name
    • last name
    • address
    • date of birth
    • gender

An Invoice entity may be described by attributes including:

    • invoice number
    • invoice date
    • invoice total

A common convention for naming attributes is to use singular nouns. Further, a naming convention may require one of:

    • All characters are in upper case.
    • All characters are in lower case.
    • Only the first character is in upper case.
    • All characters are lower case, but each subsequent part of a multipart name has the first character capitalized

Using the last convention mentioned, some examples of attribute names:

    • lastName for last name
    • empLastName for employee last name
    • deptCode for department code
    • prodCode for product code
    • invNum for invoice number

In practice a naming convention is important, and you should expect the organization you are working for to have a standard approach for naming things appearing in a model. A substantial data model will have tens, if not into the hundreds, of entity types, many more attributes and relationships. It becomes important to easily understand the concept underlying a specific name; a naming convention can be helpful.

There are many ways we can look at attributes including whether they are atomic, composite, single-valued, etc. We consider these next.


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