ER diagram makerfrom plain language, free.

erDiagram
  CUSTOMER ||--o{ ORDER : places
  CUSTOMER ||--o{ ADDRESS : "ships to"
  CUSTOMER ||--o{ REVIEW : writes
  ORDER ||--|{ ORDER_ITEM : contains
  ORDER ||--o| PAYMENT : "paid by"
  ORDER }o--|| ADDRESS : "delivered to"
  PRODUCT ||--o{ ORDER_ITEM : "ordered as"
  PRODUCT ||--o{ REVIEW : receives
  CATEGORY ||--o{ PRODUCT : groups
  CUSTOMER {
    int id PK
    string email UK
    string name
    datetime created_at
  }
  ADDRESS {
    int id PK
    int customer_id FK
    string line1
    string city
    string postcode
    string country
  }
  ORDER {
    int id PK
    int customer_id FK
    int address_id FK
    string status
    decimal total
    datetime placed_at
  }
  ORDER_ITEM {
    int order_id PK, FK
    int product_id PK, FK
    int quantity
    decimal unit_price
  }
  PRODUCT {
    int id PK
    int category_id FK
    string name
    string sku UK
    decimal price
    int stock
  }
  CATEGORY {
    int id PK
    string name
    int parent_id FK
  }
  PAYMENT {
    int id PK
    int order_id FK
    string provider
    string status
    decimal amount
  }
  REVIEW {
    int id PK
    int customer_id FK
    int product_id FK
    int rating
    string body
  }