Describe your practical experience working with SQL database management systems and give examples of solved problems.

In my practice, I have worked with relational databases such as PostgreSQL and MySQL. The main tasks included creating and optimizing queries for data retrieval, updating and deleting records, as well as designing database schemas.

For example, for an order tracking project, I wrote an SQL query that joined several tables (JOIN) to obtain information about customers and their orders over the last month:

SELECT customers.name, orders.order_date, orders.total_amount
FROM customers
JOIN orders ON customers.id = orders.customer_id
WHERE orders.order_date >= CURRENT_DATE - INTERVAL '30 days';

I also used transactions to ensure data integrity when updating multiple related tables, such as when placing an order and deducting stock.

In Python, I used libraries such as SQLAlchemy and psycopg2 to interact with the database, which allowed me to write more readable and maintainable code.