Exercise 3: select_related's JOIN vs. with()'s Batched WHERE IN — Possible Solution
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DJANGO'S select_related
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Per this chapter, Django's select_related('parent') fetches the related rows in exactly ONE query, using a genuine SQL JOIN - the main table and the related table are combined into a single query result set at the database level.

LARAVEL'S with()
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Per this chapter, Eloquent's with('parent') solves the identical N+1 problem through a genuinely different mechanism: it runs a SECOND, separate query - a batched WHERE id IN (...) clause built from every parent ID collected out of the first query's results - and then stitches the two separate result sets together afterward, in PHP memory, rather than at the database level.

THE REAL DIFFERENCE
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Per this chapter, both approaches fully eliminate the N+1 pattern (neither one issues one query per row), but they do it with a genuinely different number and kind of underlying SQL query: Django's select_related is one query using a JOIN; Eloquent's with() is two queries, neither one a JOIN, combined afterward in application code rather than by the database itself. Neither approach is wrong - they're just different, verified underlying mechanisms that happen to produce the same practical outcome (no N+1) through different means.

WHY THIS WORKS AS AN ANSWER
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It correctly describes Django's select_related as a single JOIN-based query, correctly describes Eloquent's with() as two queries combined via a batched WHERE IN and in-memory stitching rather than a JOIN, and correctly frames both as valid, different solutions to the same underlying problem.