app/db/database.py

import os
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy.orm import declarative_base

SQLALCHEMY_DATABASE_URL = os.getenv(
    "DATABASE_URL",
    "sqlite:///./data_analyst_agent.db"
)

engine_kwargs = {}
if SQLALCHEMY_DATABASE_URL.startswith("sqlite"):
    engine_kwargs["connect_args"] = {"check_same_thread": False}

engine = create_engine(SQLALCHEMY_DATABASE_URL, **engine_kwargs)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

Base = declarative_base()