Drizzle ERD Generator

Generate Mermaid ERD diagrams from Drizzle ORM schema files.

When to Use

• Database schema visualization needed
• Understanding table relationships
• Documentation for DB structure
• PR review of schema changes

Process

1. Find schema files - Locate Drizzle table definitions (usually schema.ts or tables.ts)
2. Parse tables - Extract table names, columns, types, and constraints
3. Identify relations - Find .references() calls and relations definitions
4. Generate Mermaid - Output ERD in Mermaid syntax

Mermaid ERD Syntax

erDiagram
    TABLE_NAME {
        type column_name PK "Primary Key"
        type column_name FK "Foreign Key"
        type column_name UK "Unique"
        type column_name "nullable"
    }

    TABLE_A ||--o{ TABLE_B : "has many"
    TABLE_A ||--|| TABLE_C : "has one"
    TABLE_A }o--|| TABLE_D : "belongs to"

Relationship Notation

Type Mapping

Output Template

erDiagram
    %% Master Tables

    %% Transaction Tables

    %% Snapshot Tables

    %% Relations

Example

From Drizzle:

export const users = sqliteTable("users", {
  id: integer("id").primaryKey(),
  name: text("name").notNull(),
  email: text("email").unique(),
});

export const posts = sqliteTable("posts", {
  id: integer("id").primaryKey(),
  userId: integer("user_id").references(() => users.id),
  title: text("title").notNull(),
});

To Mermaid:

erDiagram
    users {
        int id PK
        string name
        string email UK
    }

    posts {
        int id PK
        int user_id FK
        string title
    }

    users ||--o{ posts : "has many"

Quick Reference

Column Markers

• PK - primaryKey()
• FK - .references()
• UK - .unique()
• Add "nullable" comment if no .notNull()

Grouping

Group related tables with Mermaid comments:

%% === Master Tables ===
%% === Transaction Tables ===