Entity Identification

Entities represent distinct objects or concepts in the real world that we need to track information about.

Common entity types:

• People (students, employees, customers)
• Places (locations, buildings, offices)
• Things (products, equipment, assets)
• Events (transactions, appointments, courses)
• Concepts (accounts, departments, categories)

Relationship Modeling

Relationships represent associations between entities.

Relationship types:

• One-to-one (1:1)
• One-to-many (1:M)
• Many-to-many (M:N)

Example: A CUSTOMER can place many ORDERS (1:M relationship) An ORDER can contain many PRODUCTS, and a PRODUCT can appear in many ORDERS (M:N relationship)

Advanced Modeling Concepts

• Weak entities and identifying relationships
• Recursive relationships
• Subtypes and supertypes (inheritance)
• Associative entities (resolving many-to-many relationships)