Page 464 - Computer_Science_F5

For the Course entity, more attributes could for example, be Duration, Credits,
Assignments, etc. For ease, we have considered just one attribute for each entity.

Step 5: Create the ERD Diagram
A more modern representation of the ERD example. Chapter Eight: Databases and Database Management Systems
FOR ONLINE READING ONLY

Student Course Professor
Student_ID Assigned Course_ID Delivers Employee_ID
StudentName CourseName ProfessorName

Deliverables:

Submit the completed E-R diagram depicting the relationships between students,
courses, and professors. Provide a brief description outlining the rationale behind
your design decisions and how the diagram accurately represents the university
database scenario. Document your work in a portifolio.

Functional dependency (b) Importance of functional

(a) Meaning of functional dependency dependencies
Functional dependency is a constraint that (i) Functional dependency helps to
determines how one attribute relates to maintain the quality of data in the
another in a relational database. It means database.
we can derive the value of one attribute (ii) It helps to define databases’
from another. For example, knowing a constraints, ensure data integrity,
student’s roll number allows us to find their and avoid data anomalies.
address and marks, meaning the address (iii) It plays a vital role in finding the
and marks are functionally dependent difference between good and bad
on the roll number. Similarly, knowing database design, thus promoting
an employee’s number lets us determine robust and impactful databases.
their name and salary, making the name
and salary functionally dependent on the (c) Types of functional dependencies
employee number. Table 8.1 illustrates There are four main types of functional
this concept. dependency which are: Multivalued

Table 8.1: Functional dependency dependency, Trivial functional dependency,
Employee Employee Employee Non-trivial functional dependency and
Number Name Salary Transitive functional dependency.
EMP01 Diana 900,000 (i) Multivalued dependency
EMP02 Juma 950,000 This type of functional dependency occurs
EMP03 Andrew 850,000 when there are multiple independent

455
Student’s Book Form Five

Computer Science Form 5.indd 455 23/07/2024 12:34