SQL 2 ER

A command-line tool to convert SQL scripts into Entity-Relationship (ER) diagrams.
Designed to work with PostgreSQL syntax.
Report a Bug · Request a Feature

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Table of Contents

• Example
• Getting Started
• Built With
• Roadmap
• Limitations
• Unsupported Features
• Acknowledgments

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Example

Input: test.sql

CREATE TABLE department (
    dep_id SERIAL PRIMARY KEY, 
    dep_name VARCHAR(30), 
    created_at TIMESTAMPTZ DEFAULT NOW()
);

CREATE TABLE employee (
    employee_id SERIAL PRIMARY KEY, 
    employee_name VARCHAR(30), 
    employee_age INT, 
    dep_id INT REFERENCES department (dep_id) ON DELETE CASCADE, 
    created_at TIMESTAMPTZ DEFAULT NOW()
);

CREATE TABLE tasks (
    task_id INT, 
    task_name TEXT
);

Command:

./sql2er-exe test.sql -o erd.svg

Output:

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Getting Started

Option 1: Download Binary

1. Download the binary from the Releases page.

2. Run the tool:

   ./sql2er-exe test.sql -o erd.svg

Option 2: Build from Source

1. Install Stack via GHCup.

2. Clone the repository and navigate to the project root.

3. Build the binary for linux:

   stack build
   cp $(stack path --local-install-root)/bin/sql2er-exe .
   ./sql2er-exe test.sql -o erd.svg

Option 3: Build WASM

1. Install wasm32-wasi-cabal from here
2. Make sure to download the 9.8 FLAVOUR.

wasm32-wasi-cabal build sql2er-wasm -f build-sql2er-wasm
cp path/to/sql2er-wasm.wasm .
python3 -m http.server

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Built With

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Roadmap

• Add Changelog
• Add Test Cases
• Support GENERATED Constraint
• Gracefully Ignore Partitions
• Support bigserial
• Add Additional Examples
• Enhance Documentation
• Add More Parsing Functions
• Support Interval Data Type
• Support 2D Arrays

For the full list of proposed features and known issues, check out the open issues.

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Limitations

• Syntax Validation:
  The parser doesn't validate SQL syntax; it extracts only the necessary information for generating ER diagrams.
• Foreign Key Constraints:
  Currently supports single-column foreign keys only.
• PostgreSQL Specific:
  Designed and tested using PostgreSQL 17.
• Function Parsing:
  Parsing stops at CREATE FUNCTION statements.

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Unsupported Features

• DETACH
• USING ...
• TABLESPACE
• NOT VALID
• VALIDATE
• INTERVAL Data Type

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Acknowledgments

This project was inspired by sqldiagram, which focuses on MySQL but lacked robust parsing capabilities.

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