Exercise 1: The Object-Relational Impedance Mismatch — Possible Solution
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Explanation:

A relational database and an object-oriented program organise the same
data in different ways. The database keeps flat tables of rows and
columns, and connects them through foreign keys: a posts table has an
author_id column pointing at a row in users. The program wants
connected objects: a user object that holds a list of post objects.
Converting between the two — writing SQL, then turning the rows that
come back into objects — is work that has to be done somewhere, and
the "impedance mismatch" is the name for that gap between the two
models.

Two concrete problems in the plain-driver example:

  1. No checking of names. The SQL is just a string, and the code used
     `user.emial` instead of `user.email`. Nothing complains when the
     program is written or compiled; it only prints "undefined" when it
     runs — perhaps in production.

  2. No types for the results. `result.rows[0]` has no known shape, so
     the editor can't autocomplete fields and TypeScript can't warn you
     if the column is renamed or the value might be missing.

(A third possible answer: every query needs the same repetitive code —
writing the SQL, passing parameters, and unpacking rows by hand.)

WHY THIS WORKS AS AN ANSWER
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It explains the mismatch as two different ways of shaping the same
data, rather than just repeating the term, and ties each problem to a
specific line of the example.