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SQL to ER Diagram

Parse CREATE TABLE statements and automatically generate ER diagrams in Mermaid format. Securely visualize your DB design entirely within the browser.

Guide: How to use & features

  • Enter or paste SQL `CREATE TABLE` statements into the text area.
  • Click the "Visualize" button to generate and display the ER diagram using Mermaid syntax.
  • Table relationships (Foreign Keys) are automatically extracted from `FOREIGN KEY` or `REFERENCES` clauses.
  • Use the "Copy Mermaid Code" button to save the generated syntax to your clipboard.
  • Your schema data is processed entirely in the browser, ensuring privacy and security.

Samples: Examples

Users and Posts (One-to-Many)

Input

CREATE TABLE users (
  id INT PRIMARY KEY,
  name VARCHAR(50)
);

CREATE TABLE posts (
  id INT PRIMARY KEY,
  user_id INT REFERENCES users(id),
  title VARCHAR(100)
);

Output

erDiagram
    users {
        INT id PK
        VARCHAR(50) name
    }
    posts {
        INT id PK
        INT user_id
        VARCHAR(100) title
    }

    posts }|--|| users : "user_id -> id"

FAQ: FAQ

  • Does it support all SQL dialects?

    It supports standard SQL CREATE TABLE syntax. Some highly specific proprietary vendor extensions may not be fully parsed as it uses a custom regex-based parser.

  • Is my data sent to a server?

    No. All processing is done locally in your browser via JavaScript. Your SQL code never leaves your computer.

  • What if relationships are not showing up?

    Ensure that your statements include FOREIGN KEY or REFERENCES clauses. The tool relies on these constraints to identify and draw relationships.

Use cases: Common Use Cases

  • Database Documentation

    Quickly visualize and document existing table structures by pasting SQL exports.

  • Schema Design Verification

    Self-check your DDL to ensure that relationships and constraints are correctly defined during the design phase.

  • Team Collaboration

    Share specific sub-system structures with your team using lightweight Mermaid syntax before generating full documentation.

Notes: Notes & Limitations

  • Limited SQL Syntax

    Statements other than CREATE TABLE (e.g., stored procedures, triggers, complex INDEX definitions) are ignored.

  • Performance with Large Schemas

    Very large schemas with dozens of tables may significantly impact browser rendering performance.

  • Syntax Errors

    Incomplete or malformed SQL statements (missing parentheses, typos) will result in parsing failures.
erDiagram USERS ||--o{ POSTS : "user_id -> id" USERS { int id PK string name } POSTS { int id PK int user_id string title }

About the SQL to ER Diagram (Mermaid) Generator

This online tool automatically generates Entity-Relationship (ER) diagrams in Mermaid.js format directly from your SQL DDL statements (CREATE TABLE).
Visualizing schemas directly from your database definitions dramatically improves efficiency during database design reviews and documentation creation.

How It Works & Privacy

This tool runs entirely in your browser using JavaScript. The SQL statements you input, including table structures and foreign key relationships, are never transmitted to any external servers.
You can safely use it to visualize the most sensitive internal database schemas without any risk of information exposure.

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