🍟 Comprehensive ERD: McDonald’s Integrated Operations System

(Focused on Order Processing, Customer Experience & Store Operations)

🔍 Business Context

This Entity-Relationship Diagram models core operations in a McDonald’s store, focusing on:

• Order flow from customer to payment

• Employee roles and store management

• Menu availability and pricing

• Customer loyalty and repeat engagement

• Basic inventory tracking (for food items)

Note: This is not a full enterprise database (e.g., supply chain or HR), but a realistic, scalable foundation for a fast-food POS system.

📚 Entities & Attributes

🔗 Relationships (with Cardinalities)

✅ Optional: Add a LoyaltyProgram entity if deeper loyalty logic is needed (e.g., points redemption, rewards).

🔒 Constraints & Business Rules

• Price must be > 0

• Order status cannot be ‘Completed’ if payment is missing

• Quantity in OrderItem ≥ 1

• Promotions can only be applied if active and within time window

• Customer must be linked to at least one order to earn loyalty points

• Menu items are marked as ‘Inactive’ if out-of-stock or discontinued

📝 Use Cases (Why This ERD Matters)

📂 Output Formats

You can copy and paste any of the following into your documentation, presentation, or database design tools.

✅ 1. Text-Based ERD (for documentation)

Entities:

- Customer
  - CustomerID (PK)
  - Name
  - Phone
  - Email
  - LoyaltyPoints
  - MembershipTier

- Store
  - StoreID (PK)
  - Name
  - Location
  - ManagerID (FK → Employee)
  - OpenHours
  - MonthlySales

- Employee
  - EmployeeID (PK)
  - Name
  - Role (Cashier, Cook, Manager)
  - StoreID (FK)
  - HireDate

- MenuItem
  - MenuItemID (PK)
  - Name
  - Description
  - Price
  - Category
  - IsActive

- Order
  - OrderID (PK)
  - OrderTime
  - Status (Pending, Preparing, Ready, Completed, Cancelled)
  - CustomerID (FK)
  - StoreID (FK)
  - TotalAmount

- OrderItem
  - OrderItemID (PK)
  - OrderID (FK)
  - MenuItemID (FK)
  - Quantity
  - LineTotal

- Payment
  - PaymentID (PK)
  - Amount
  - Method (Cash, CreditCard, MobilePay)
  - OrderID (FK)
  - Timestamp

- Promotion
  - PromotionID (PK)
  - Code
  - DiscountType
  - DiscountValue
  - ActiveDate
  - ExpireDate
  - AppliesTo

Relationships:
- Customer "1" -- "0..*" Order
- Order "1" -- "0..*" OrderItem
- Order "1" -- "1" Payment
- Order "1" -- "1" Store
- Store "1" -- "0..*" Employee
- MenuItem "1" -- "0..*" OrderItem
- Promotion "0..*" -- "1" Order (conditional on active status)

✅ 2. Mermaid.js Version (for Markdown, Notion, Obsidian)

erDiagram
    CUSTOMER ||--o{ ORDER : "places"
    STORE ||--o{ ORDER : "serves"
    STORE ||--o{ EMPLOYEE : "employs"
    STORE ||--o{ MENU_ITEM : "sells"
    ORDER ||--o{ ORDER_ITEM : "contains"
    ORDER ||--o{ PAYMENT : "has"
    MENU_ITEM ||--o{ ORDER_ITEM : "appears in"
    PROMOTION ||--o{ ORDER : "applies to"

    CUSTOMER {
        int CustomerID PK
        string Name
        string Phone
        string Email
        int LoyaltyPoints
        string MembershipTier
    }

    STORE {
        int StoreID PK
        string Name
        string Location
        int ManagerID FK
        string OpenHours
        decimal MonthlySales
    }

    EMPLOYEE {
        int EmployeeID PK
        string Name
        string Role
        int StoreID FK
        date HireDate
    }

    MENU_ITEM {
        int MenuItemID PK
        string Name
        string Description
        decimal Price
        string Category
        boolean IsActive
    }

    ORDER {
        int OrderID PK
        datetime OrderTime
        string Status
        int CustomerID FK
        int StoreID FK
        decimal TotalAmount
    }

    ORDER_ITEM {
        int OrderItemID PK
        int OrderID FK
        int MenuItemID FK
        int Quantity
        decimal LineTotal
    }

    PAYMENT {
        int PaymentID PK
        decimal Amount
        string Method
        int OrderID FK
        datetime Timestamp
    }

    PROMOTION {
        int PromotionID PK
        string Code
        string DiscountType
        decimal DiscountValue
        datetime ActiveDate
        datetime ExpireDate
        string AppliesTo
    }

✅ 3. PlantUML Version 

' McDonald's Order System ERD (PlantUML)

package "McDonald's Operations" {
  entity "Customer" {
    - CustomerID (PK)
    - Name
    - Phone
    - Email
    - LoyaltyPoints
    - MembershipTier
  }

  entity "Store" {
    - StoreID (PK)
    - Name
    - Location
    - ManagerID (FK → Employee)
    - OpenHours
    - MonthlySales
  }

  entity "Employee" {
    - EmployeeID (PK)
    - Name
    - Role (Cashier, Cook, Manager)
    - StoreID (FK → Store)
    - HireDate
  }

  entity "MenuItem" {
    - MenuItemID (PK)
    - Name
    - Description
    - Price
    - Category (Burger, Drink, Side)
    - IsActive
  }

  entity "Order" {
    - OrderID (PK)
    - OrderTime
    - Status (Pending, Preparing, Ready, Completed)
    - CustomerID (FK → Customer)
    - StoreID (FK → Store)
    - TotalAmount
  }

  entity "OrderItem" {
    - OrderItemID (PK)
    - OrderID (FK → Order)
    - MenuItemID (FK → MenuItem)
    - Quantity
    - LineTotal
  }

  entity "Payment" {
    - PaymentID (PK)
    - Amount
    - Method (Cash, CreditCard)
    - OrderID (FK → Order)
    - Timestamp
  }

  entity "Promotion" {
    - PromotionID (PK)
    - Code (e.g., WELCOME10)
    - DiscountType (Percentage, Fixed)
    - DiscountValue
    - ActiveDate
    - ExpireDate
    - AppliesTo
  }

  Customer "1" -- "0..*" Order : "places"
  Order "1" -- "0..*" OrderItem : "contains"
  Order "1" -- "1" Payment : "has"
  Order "1" -- "1" Store : "is placed at"
  Store "1" -- "0..*" Employee : "employs"
  MenuItem "1" -- "0..*" OrderItem : "appears in"
  Promotion "0..*" -- "1" Order : "applies to"
}

🔍 Future Extensions (Optional)

If you’d like to expand this ERD, consider adding:

• Inventory → Tracks stock levels, reorder points, supplier info

• Shift Schedule → Daily shifts, break times, shift assignments

• Supplier → Who supplies ingredients (e.g., “Cheese Supplier”)

• Seasonal Menus → Special promotions (e.g., “Summer BBQ Menu”)

• Geolocation → For delivery or pickup tracking

🚀 Final Thoughts

This ERD is realistic, scalable, and aligned with McDonald’s operations — it reflects actual POS workflows, employee roles, and customer behavior.

✅ You now have a complete, ready-to-use ERD for a McDonald’s system — whether for a school project, business analysis, or technical design.