Entity-Relationship Model
ER Components
- Entity: Real-world object (Student, Course)
- Attribute: Property of entity (name, age)
- Relationship: Association between entities (enrolls)
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LearnStep 1 of 2
ER Model
Learning Objectives
- •Understand ER concepts
- •Draw ER diagrams
- •Convert ER to relational
Lesson Outline
LearnStep 1/2
ER Model
Relationship Cardinalities
Attribute Types
- Simple: Atomic (age, name)
- Composite: Divisible (address → street, city, zip)
- Derived: Computed (age from DOB)
- Multi-valued: Multiple values (phone numbers)
- Key: Unique identifier (student_id)