ER Diagram

Entity-Relationship Diagram

Entities

• Employee — base entity for all staff; extended by Driver and Logistician
• Driver — employee who performs trips; has a DriverLicense
• Logistician — employee who plans trips; can manage other logisticians (recursive relationship)
• Truck — vehicle assigned to a trip
• Trip — a single freight run performed by a driver, planned by a logistician, using a truck
• Order — a freight order placed by a client company; transported within a trip
• TripExpense — an expense recorded for a trip (fuel, toll, parking, service)
• ClientCompany — a company that places orders

Key Relationships

• Employee → Driver, Logistician — complete exclusive inheritance
• Driver — has — DriverLicense (1:1)
• Logistician — manages — Logistician (recursive, 0:N to 0:1)
• Trip — transports — Order (N:M)
• Trip — contains — TripExpense (1:N)
• ClientCompany — places — Order (1:N)