Logistics Shipment Database Schema

erDiagram
  CUSTOMER ||--o{ SHIPMENT : books
  SHIPMENT ||--|{ PACKAGE : contains
  SHIPMENT ||--|{ LEG : "moves in"
  HUB ||--o{ LEG : "origin of"
  VEHICLE ||--o{ LEG : carries
  PACKAGE ||--o{ TRACKING_EVENT : logs
  TRACKING_EVENT ||--o| PROOF_OF_DELIVERY : "may have"
  CUSTOMER {
    int id PK
    string name
    string gstin
  }
  SHIPMENT {
    int id PK
    int customer_id FK
    string awb_no
    string service_level
  }
  PACKAGE {
    int id PK
    int shipment_id FK
    decimal weight_kg
    string barcode
  }
  LEG {
    int id PK
    int shipment_id FK
    int from_hub_id FK
    int vehicle_id FK
    datetime departed_at
  }
  HUB {
    int id PK
    string code
    string city
  }
  VEHICLE {
    int id PK
    string registration
    string type
  }
  TRACKING_EVENT {
    int id PK
    int package_id FK
    string status
    datetime at
    string location
  }
  PROOF_OF_DELIVERY {
    int id PK
    int event_id FK
    string receiver_name
    string photo_url
  }