Mermaid

Create Mermaid entity relationship diagrams (ERD) from SQL migration files or database schemas.

Process:

1. Parse Arguments:

   • First argument: Source path (SQL files or directory)
   • Second argument: Output path (optional, defaults to docs/erd.md)

2. Find SQL/Schema Files:

   • Look for SQL files: *.sql, *.ddl
   • Check common locations if no path provided:
     • migrations/, db/migrations/, schema/
     • database/, sql/
   • Support multiple database formats:
     • PostgreSQL, MySQL, SQLite
     • Migration files (Rails, Django, Flyway, etc.)

3. Extract Schema Information:

   • Parse CREATE TABLE statements
   • Extract table names, columns, and data types
   • Identify primary keys, foreign keys, and relationships
   • Handle indexes and constraints

4. Generate Mermaid ERD:

   erDiagram
     CUSTOMER ||--o{ ORDER : places
     ORDER ||--|{ LINE-ITEM : contains
     CUSTOMER {
       string name
       string email
       int id PK
     }
   

5. Validate Diagram:

   • If mermaid-cli is available: npx -p @mermaid-js/mermaid-cli mmdc -i output.md -o temp.svg
   • Alternative validation: Check syntax manually
   • Clean up temporary files

6. Output Options:

   • Single file with all entities
   • Separate files per schema/database
   • Include relationship descriptions

Example Usage:

• /mermaid migrations/ - Create ERD from all SQL files in migrations
• /mermaid schema.sql docs/database-erd.md - Create ERD from specific file
• /mermaid "db/**/*.sql" erd/ - Create ERDs for all SQL files

Source: $ARGUMENTS