Exercise 2: Dollar-Quoting vs. MySQL's DELIMITER Dance — Possible Solution
====================================================================

WHAT DOLLAR-QUOTING IS
------------------------------
Per this chapter, "the $$ ... $$ around the function body is
dollar-quoting — a genuine Postgres-specific convenience letting a
multi-line body be written without escaping internal quotes." Rather
than wrapping a function's body in ordinary single quotes (which would
require escaping every internal single quote used within the body
itself), Postgres allows a body to be delimited by a pair of matching
$$ markers (or a custom $tag$ ... $tag$ pair), letting the body's own
text — including any quotes it contains — be written literally,
without any escaping.

WHY MYSQL NEEDS THE DELIMITER DANCE
------------------------------
Per this chapter, "MySQL's own DELIMITER // convention exists
specifically because semicolons inside a stored procedure body would
otherwise be misread as the end of the outer CREATE PROCEDURE
statement, forcing a temporary delimiter change and a matching // at
the end." MySQL's client normally treats a semicolon as "this
statement is finished, send it now." Since a stored procedure body
itself is full of semicolons (one after each internal statement), the
client would incorrectly think the CREATE PROCEDURE statement ended
partway through the body, at the first internal semicolon it
encountered. To work around this, MySQL requires temporarily changing
the statement terminator to something else (commonly //) before
defining the procedure, and switching it back afterward — an extra,
easy-to-forget ceremony surrounding every procedure/function
definition.

WHY DOLLAR-QUOTING IS A GENUINE ERGONOMIC IMPROVEMENT
------------------------------
Postgres's dollar-quoting sidesteps this problem entirely by using a
DIFFERENT delimiter ($$ or $tag$) that has nothing to do with the
semicolons used inside the body — the semicolons inside a PL/pgSQL
function body never risk being misread as ending the outer CREATE
FUNCTION statement, because the body's own boundary is marked by a
completely distinct symbol. This means there's no need to change and
then restore the statement delimiter at all — no DELIMITER // before,
no // after, just the function body written directly inside its own
$$ ... $$ markers.

WHY THIS WORKS AS AN ANSWER
------------------------------
It explains dollar-quoting's actual mechanism, explains precisely WHY
MySQL's DELIMITER convention is necessary in the first place (the
semicolon-ambiguity problem), and connects the two to show specifically
what extra ceremony dollar-quoting removes.