FastAPI - Database Integration
Find the bug in this FastAPI connection pooling setup:
```python
engine = create_engine("postgresql://user:pass@localhost/db", pool_size=10, max_overflow=5)
SessionLocal = sessionmaker(bind=engine)
@app.get("/data")
async def get_data():
db = SessionLocal()
result = db.execute("SELECT * FROM data_table")
return result.fetchall()
```