This project provides a Python-based Model Context Protocol (MCP) server that allows a Large Language Model (LLM) to securely interact with SQL Server or PostgreSQL databases in a read-only capacity.

• Connects to PostgreSQL or SQL Server databases.
• Provides MCP tools to:
  • get_schema: Fetch database schema (all tables or a specific table).
  • query_data: Execute read-only SELECT queries.
• Enforces read-only access through query validation.

1. Environment: This project uses uv for environment and dependency management. Ensure you have uv installed (pip install uv).

2. Dependencies: The necessary dependencies have already been installed into the .venv directory using uv add. If you need to reinstall:

   uv sync

3. Configuration:

   • Copy the example environment file:

     cp .env.example .env

   • Edit the .env file and set the DATABASE_URL variable to your database connection string. Examples are provided in the file for PostgreSQL and SQL Server (using pyodbc).
   • Choose the appropriate SQLAlchemy driver prefix (postgresql+asyncpg, mssql+pyodbc, etc.) based on your database and installed driver.
   • Ensure you have the necessary database drivers installed (e.g., psycopg2-binary is included, but for SQL Server, you might need pyodbc and system-level ODBC drivers).
   • Configure the TRANSPORT (e.g., stdio or sse), HOST, and PORT as needed.

You can run the server locally for testing using the MCP development tools:

# Activate the virtual environment (optional, uv run handles it)
# source .venv/bin/activate  # Linux/macOS
# .\.venv\Scripts\activate  # Windows

# Run with uv (recommended)
uv run mcp dev src/main.py

# Or run directly if environment is activated
# mcp dev src/main.py

This will start the MCP Inspector, allowing you to interact with the get_schema and query_data tools.

You can also run the server directly using the configured transport (stdio or sse):

# Ensure .env is configured (especially TRANSPORT)
uv run python src/main.py

Refer to the mcp install command and the MCP client's documentation for integrating the server. You'll typically provide the command to run the server (using uv run python src/main.py or similar) and necessary environment variables.

Example Stdio Configuration (Conceptual):

{
  "mcpServers": {
    "sql-explorer": {
      "command": "uv",
      "args": ["run", "python", "c:/path/to/sql-mcp/src/main.py"],
      "envFiles": ["c:/path/to/sql-mcp/.env"],
      "env": {
          "TRANSPORT": "stdio"
          // DATABASE_URL will be picked from .env file
      }
    }
  }
}

Example SSE Configuration (Conceptual):

Ensure TRANSPORT=sse, HOST, and PORT are set in .env.

{
  "mcpServers": {
    "sql-explorer": {
      "transport": "sse",
      "url": "http://localhost:8051/sse" // Or configured HOST/PORT
    }
  }
}