# Entity-Relationship Diagrams - Domain Specific Language ## Goals * Describe all possible cases according to MERISE * Be simple to read and write by a human user * Be simple to parse by a machine ## Example ``` entities: user: id: UUID password_hash: VARCHAR(250) role: VARCHAR(10) created_at: DATETIME updated_at: DATETIME url: id: VARCHAR(250) custom_id: VARCHAR(250) source_url: TEXT short_url: VARCHAR(250) created_at: DATETIME updated_at: DATETIME expires_at: DATETIME relationships: manages_urls: links: - user: eq: 1 - url: gte: 0 lte: n properties: {} ```