Databases Illuminated, 4th Edition

3.3 Attributes

The attributes of an entity are the defining properties or qualities of the entity type. For the Student entity type, the defining properties might be the student’s ID, name, major, and number of credits accumulated. The attributes are the representation in the model of those properties, namely stuId, lastName, firstName, major, and credits. Normally, an entity instance will have a value for each of its attributes. An attribute is represented in an ER diagram by an oval with the name of the attribute inside. A line connects the attribute oval to the rectangle for the entity set it describes.

Figure 3.1 shows several examples of attributes connected to their entity sets. Just as with entities, different designers may disagree about ...