Premier League Predictor: FastAPI & PostgreSQL — Chapter 9, Exercise 2
====================================================

TASK
Explain what "removing" a relegated team from next season's SeasonTeam
set actually means in this implementation, and confirm whether that
team's own historical record in the old season is affected at all.

SOLUTION

"Removing" a relegated team means exactly one thing in
rollover_season: that team's row simply doesn't appear in the
survivors list (since it's part of old_table's own bottom three,
sliced off by old_table[:-RELEGATION_COUNT]), so no matching
SeasonTeam row is ever created for it in new_season. Nothing is
deleted, updated, or otherwise touched — the "removal" is really just
an omission: the team is absent from the set of teams being carried
forward, not actively taken away from anything.

The relegated team's own historical record in the old season is
completely unaffected. Its original SeasonTeam row for old_season_id
was created back whenever that team was originally added to that
season (Chapter 3), and rollover_season never queries, modifies, or
deletes anything in the old_season's own SeasonTeam rows at all — it
only reads old_table (built from fixtures and results, not from
SeasonTeam directly) and writes new rows scoped to new_season_id. The
relegated team's real record of having competed in that specific old
season — and every fixture, prediction, and result tied to it — remains
exactly as it was, permanently, matching Chapter 2's own original design
that Team and SeasonTeam rows persist as real history rather than being
overwritten or erased when circumstances change.

WHY THIS WORKS AS AN ANSWER
----------------------------
It correctly identifies "removal" here as an omission (no new row
created) rather than a deletion, and directly confirms — by pointing to
exactly which rows rollover_season reads from and writes to — that the
old season's own historical SeasonTeam data is never touched by this
route at all.