Database Reference
In-Depth Information
FACULT Y
FacultyID
FirstName
LastName
Department
JobCode
JobCode
PROFESSOR
INSTRUCTOR
FacultyID (FK)
FacultyID (FK)
Rank
Committee
Supervisor
TeachingLoad
Figure 2.9
Incomplete categorization relationship.
speciic entities PROFESSOR and INSTRUCTOR. Such a relationship is called a
categorization
relationship
. Figure 2.9 shows one type of categorization relationship in the IDEF1X standard.
In Figure 2.9, the super type entity FACULTY is represented by a rectangle. he subtype enti-
ties PROFESSOR and INSTRUCTOR are represented by round-cornered rectangles. Here, the
attribute Supervisor refers to the faculty who supervises the instructor. he
Category
icon is
a
discriminator
that distinguishes a faculty member as a professor or an instructor. he attribute
JobCode is used for classiication. here are two types of categorization relationships. If at least
one subtype entity is not included in the relationship, the categorization relationship is
incom-
plete
, which is represented by a single horizontal line in the Category icon as shown in Figure 2.9.
When all the subtype entities are included in the relationship, the categorization relationship is
complete
, which is denoted by two horizontal lines in the
Category
icon. For example, suppose
that we have one more FACULTY category, researcher. By adding this category, we have generated
a complete categorization relationship as shown in Figure 2.10.
FACULT Y
FacultyID
FirstName
LastName
Department
JobCode
PROFESSOR
RESEARCHER
INSTRUCTOR
FacultyID (FK)
FacultyID (FK)
FacultyID (FK)
Rank
Committee
Rank
Lab
Supervisor
Te achingLoad
Figure 2.10
Complete categorization relationship.
