Database Schema Diagrams

Why Use Mermaid

• Import SQL DDL — Paste CREATE TABLE statements and get an ER diagram instantly
• Auto-detect relationships — Foreign keys are converted to crow's foot notation
• Multiple SQL dialects — PostgreSQL, MySQL, SQLite, and SQL Server supported
• Visual documentation — Generate diagrams for database reviews and onboarding
• Export anywhere — PNG for docs, SVG for presentations, PDF for printouts

Example Diagram

erDiagram
    USER ||--o{ ORDER : places
    USER ||--o{ ADDRESS : "has"
    ORDER ||--|{ ORDER_ITEM : contains
    ORDER ||--|| PAYMENT : "paid by"
    PRODUCT ||--o{ ORDER_ITEM : "included in"
    CATEGORY ||--o{ PRODUCT : groups

    USER {
        uuid id PK
        string email UK
        string name
        string password_hash
        timestamp created_at
        timestamp updated_at
    }
    ORDER {
        uuid id PK
        uuid user_id FK
        string status
        decimal subtotal
        decimal tax
        decimal total
        timestamp ordered_at
    }
    ORDER_ITEM {
        uuid id PK
        uuid order_id FK
        uuid product_id FK
        int quantity
        decimal unit_price
        decimal line_total
    }
    PRODUCT {
        uuid id PK
        string name
        string sku UK
        decimal price
        int stock
        uuid category_id FK
        text description
    }
    CATEGORY {
        uuid id PK
        string name UK
        uuid parent_id FK
        string slug UK
    }
    ADDRESS {
        uuid id PK
        uuid user_id FK
        string street
        string city
        string state
        string zip
        string country
    }
    PAYMENT {
        uuid id PK
        uuid order_id FK
        string provider
        string transaction_id UK
        decimal amount
        string status
        timestamp paid_at
    }

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Frequently Asked Questions