What types of databases or data warehouses have you used in your practice?

In practice, I have used the following types of databases and data stores:

• Relational databases (SQL): PostgreSQL, MySQL, SQLite. Used for storing structured data with support for complex queries and transactions.
• Document-oriented databases (NoSQL): MongoDB. Used for flexible storage of JSON-like documents, especially when the data structure may change frequently.
• Key-value stores: Redis. Used for caching and quick data access.
• File storage: Amazon S3 for storing large files and backups.

Example of connecting to PostgreSQL in Python using the psycopg2 library:

import psycopg2

conn = psycopg2.connect(
    dbname="mydb",
    user="user",
    password="password",
    host="localhost"
)
cur = conn.cursor()
cur.execute('SELECT * FROM users')
rows = cur.fetchall()
for row in rows:
    print(row)
cur.close()
conn.close()