= Conceptual Design – ER Diagram and Data Requirements =

== ER Diagram ==

The following figure presents the conceptual Entity–Relationship (ER) diagram of the
Online Learning Platform Management System (OLPMS). It illustrates the main entities,
their attributes, and the relationships between users, instructors, courses, enrollments,
payments, subscriptions, learning content, and certificates.

[[Image(OLPMS_ER_Diagram.png, width=600)]]


== Data Requirements ==

=== Entities ===

* **Users**
  * user_id (primary key)
  * first_name
  * last_name
  * email
  * password

* **Instructors**
  * instructor_id (primary key)
  * bio
  * expertise

* **Course**
  * course_id (primary key)
  * name
  * price
  * status

* **Enrollment**
  * enrollment_id (primary key)
  * enroll_date
  * completion_status
  * progress_percentage

* **Payment**
  * payment_id (primary key)
  * amount

* **SubscriptionPlan**
  * plan_id (primary key)
  * name
  * price
  * duration_months
  * access_type

* **Certificate**
  * certificate_id (primary key)
  * issue_date
  * certificate_code
  * status

=== Relationships ===

* A **User** can make multiple **Payments** (1:N)
* A **User** can enroll in multiple **Courses** through **Enrollment** (1:N)
* An **Instructor** can upload and manage multiple **Courses** (1:N)
* A **Course** can have multiple **Enrollments** (1:N)
* A **SubscriptionPlan** can be used by multiple **Users** (1:N)
* A **Certificate** is issued for a completed **Enrollment** (1:1)