Turn a data model into an entity-relationship (ER) diagram. Use when asked to design a schema, model data, show how tables/entities relate, or diagram a database. Produces a ready-to-render Mermaid ER diagram (renders live, exportable as PNG/SVG) plus key attributes, cardinality, and design notes.
Start a fresh conversation. Replace the highlighted placeholders.
Use entity-relationship-diagram to create a Mermaid ER diagram for [domain], showing [entities, relationships, and cardinalities] with key attributes, foreign keys, and concise design notes.
Required inputs
[domain]
[entities, relationships, and cardinalities]
User-approved starter prompt based on a pinned source version; check current skill requirements before running. Task evidence ↗
SKILL.md
name: entity-relationship-diagramdescription: "Turn a data model into an entity-relationship (ER) diagram. Use when asked to design a schema, model data, show how tables/entities relate, or diagram a database. Produces a ready-to-render Mermaid ER diagram (renders live, exportable as PNG/SVG) plus key attributes, cardinality, and design notes."
Entity-Relationship Diagram Skill
Before you write a migration, it pays to see the data model: the entities, their key fields, and how they
relate (one-to-many, many-to-many). This skill turns a described domain into a clean Mermaid ER diagram
with proper cardinality notation and the attributes that matter.
Required Inputs
Ask for these only if they aren't already provided:
The entities — the core objects/tables (User, Order, Product…).
Relationships — how they relate, and the cardinality (a user has many orders, an order has many line items).
Key attributes — the important fields per entity (especially keys); full column lists aren't required.
The domain — what the system does, so the model is realistic.
Output Format
[Domain] — data model
One line on the scope of the model.
erDiagram
USER ||--o{ ORDER : places
ORDER ||--|{ LINE_ITEM : contains
PRODUCT ||--o{ LINE_ITEM : "appears in"
USER {
uuid id PK
string email
string name
}
ORDER {
uuid id PK
uuid user_id FK
datetime created_at
string status
}
LINE_ITEM {
uuid id PK
uuid order_id FK
uuid product_id FK
int qty
}
PRODUCT {
uuid id PK
string name
decimal price
}