Example to Minimize Partial Dependency
Original Table (CourseEnrollment):
StudentID |
CourseID |
CourseName |
Instructor |
Department |
---|---|---|---|---|
1001 |
CS101 |
Introduction to Computer Science |
Dr. Lee |
Computer Science |
1001 |
Math202 |
Calculus II |
Dr. Miller |
Mathematics |
1002 |
HIS101 |
World History |
Dr. Khan |
History |
1002 |
ENG205 |
Literature |
Prof. Jackson |
English |
1003 |
CS202 |
Data Structures |
Dr. Lee |
Computer Science |
Here the department is partially dependent on the instructor. While an instructor typically teaches courses in his or her own department, an instructor may also teach courses from other departments. This creates a partial dependency. Normalization To reduce partial dependency,
we can decompose the table into two separate tables:
- CourseEnrollment (StudentID, CourseID, CourseName, Instructor): This table holds information about student enrollments in courses. .
- InstructorDepartment (Instructor, Department): This table associates instructors with their primary department.
Course Enrollment:
StudentID |
CourseID |
CourseName |
Instructor |
---|---|---|---|
1001 |
CS101 |
Introduction to Computer Science |
Dr. Lee |
1001 |
Math202 |
Calculus II |
Dr. Miller |
1002 |
HIS101 |
World History |
Dr. Khan |
1002 |
ENG205 |
Literature |
Prof. Jackson |
1003 |
CS202 |
Data Structures |
Dr. Lee |
InstructorDepartment:
Instructor |
Department |
---|---|
Dr. Lee |
Computer Science |
Dr. Miller |
Mathematics |
Dr. Khan |
History |
Prof. Jackson |
English |
Dr. Lee |
Computer Science |
Partial Dependency in DBMS
Database Management Systems (DBMS) design and optimize their databases for working, expecting partial dependency. It is something like a functional or strong dependency that makes it possible to show a constrained relationship between two or more attributes in a table. In this essay, we will discuss partial reliances, how to overcome them, and how to eliminate them while creating database models.
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