This is necessary so that the grading system can have the following properties: Many-to-many relations typically require an additional table. User Course (via the CourseEnrollment relation table with two foreign keys: userId and courseId).The first thing to note about the diagram is that every entity maps to a database table. The diagram below adds the columns relevant for each entity and foreign keys to describe the relationships between the entities. The entities can be visualized to demonstrate how they would be represented in a relational database (in this case PostgreSQL). For example, a user represents a person, whereas a course is an intangible concept. Note: An entity represents either a physical object or an intangible concept. Additionally, a TestResult is also related to the teacher who graded the test.
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