No More Raw SQL: SQLAlchemy & ORMs
summary
A Marketplace microservice with five tables (customers, addresses, orders, order_items, items) moves from raw sqlite3 SQL to SQLAlchemy core and then declarative ORM models; multi-join queries become a two-line select, inserts become session.add + session.commit, and migrations use alembic. The demo logs SQL via echo, contrasts connection.commit vs engine.begin, exposes the N+1 problem (loading three customers issues four queries and would blow up with hundreds or thousands), and shows eager loading and func.sum optimisations that actually reduce queries and commit successfully.
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chapters (16)
- 0:00SQLAlchemy & ORMs intro
- 1:04From raw SQL to core
- 7:07Sample microservice
- 8:56Raw SQL queries
- 11:07SQLAlchemy engine
- 12:54SELECT with SQLAlchemy
- 14:42Committing data
- 16:30Adding ORMs
- 19:17Tables to Python classes
- 21:03Querying data with ORMs
- 23:50Complex ORM queries
- 24:33Inserting with ORMs
- 27:00Lazy loading
- 29:04N+1 problem fix
- 30:09SQL functions
- 30:53Summary
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