Database

Database introspection and query execution via SQLAlchemy. Supports any SQLAlchemy-compatible database (PostgreSQL, MySQL, SQLite, Oracle, MS SQL Server, etc.).

Highlights

• Connection pooling with automatic health checks
• Vertical result formatting optimized for LLM consumption
• Parameterized queries for safe SQL execution
• Large results truncated at 4000 characters
• Per-URL connection pools with 1-hour recycling

Functions

Function	Description
db.tables(db_url, ...)	List table names in the database
db.schema(table_names, db_url)	Get schema definitions for tables
db.query(sql, db_url, ...)	Execute SQL and return formatted results

Key Parameters

Parameter	Type	Description
db_url	str	SQLAlchemy connection string (required)
filter	str	Substring to filter table names (tables only)
ignore_case	bool	Case-insensitive filter matching (tables only, default: False)
table_names	list[str]	Tables to inspect (schema only)
params	dict	Query parameters for safe substitution (query only)

Examples

# Get database URL from project config
db_url = proj.attr("myproject", "db_url")

# List all tables
db.tables(db_url=db_url)

# Filter tables
db.tables(db_url=db_url, filter="user")

# Get schema for tables
db.schema(["users", "orders"], db_url=db_url)

# Execute queries (parameterized for safety)
db.query("SELECT * FROM users LIMIT 5", db_url=db_url)
db.query(
    "SELECT * FROM users WHERE status = :status",
    db_url=db_url,
    params={"status": "active"}
)

Project Configuration

Configure database connections in onetool.yaml:

projects:
  myapp:
    path: /path/to/project
    attrs:
      db_url: postgresql://localhost/myapp

  demo:
    path: .
    attrs:
      db_url: sqlite:///demo/db/northwind.db

Supported Databases

Any SQLAlchemy-compatible database:

• SQLite: sqlite:///path/to/db.db
• PostgreSQL: postgresql://user:pass@host/db
• MySQL: mysql://user:pass@host/db

Configuration

Setting	Default	Description
db.max_chars	4000	Maximum output characters

tools:
  db:
    max_chars: 8000  # Larger output

Security

• Queries are read-only by default
• Use parameterized queries for user input
• Configure max_chars to prevent excessive output