You need to read data from a MySQL table, but you cannot store the credentials in your notebook. How would you write code to handle this securely? Provide a code structure.

Avoid hard‑coding credentials in the notebook. The most common approach is to keep them in environment variables or a secrets store and read them at runtime. For example, in a Jupyter notebook you can use python‑dotenv to load a .env file that is excluded from version control:

from dotenv import load_dotenv
import os
import mysql.connector

load_dotenv()  # loads .env into os.environ
host = os.getenv("DB_HOST")
user = os.getenv("DB_USER")
password = os.getenv("DB_PASSWORD")
db = os.getenv("DB_NAME")

conn = mysql.connector.connect(host=host, user=user, password=password, database=db)
cur = conn.cursor()
cur.execute("SELECT * FROM my_table")
rows = cur.fetchall()

If you are on AWS, you can fetch the secret from Secrets Manager:

import boto3, json
client = boto3.client('secretsmanager')
secret = client.get_secret_value(SecretId='mydbsecret')
creds = json.loads(secret['SecretString'])
conn = mysql.connector.connect(**creds)

Both patterns keep credentials out of the notebook and version control, allow rotation, and can be integrated with CI/CD pipelines. The runtime cost is negligible; the database query itself is O(n) in the number of rows returned. This solution is suitable for junior to mid‑level engineers and scales to production workloads.