Lesson 3 — Filter and sort through relationships

Continue in the SAME Python console after lesson 2. Type the commands from
console.py in order. No further model changes or imports are needed.

Starting again? Unzip the bundle, open Python in its folder and run:
    exec(open("start-here.py").read())
This rebuilds the exact state of lessons 1 and 2, using the four included CSVs.
Do not rerun the bootstrap in an already populated session.
The database is in memory: closing Python discards it. No model/database files
are written. The CSV fixtures contain fictional data.

Expected results before display limits: four Florence invoices, twelve Florence
rows, and nine Florence rows dated 2026-10-01 or later. ASC is the default;
DESC reverses order. Equal sort values have no guaranteed relative order.
Fields used in WHERE or ORDER BY do not have to be selected.
No explicit column aliases are required: result names are assigned automatically.

Uses the same API as lessons 1 and 2. Official release installation verification
is still pending; see /status/#course. Video timing is edited; results are real.
