Here’s a MySQL query issued by some Perl code:

$db->do(q{
    CREATE TEMPORARY TABLE byline_age (
        byline_id int PRIMARY KEY,
        last_used int not null
    )
    SELECT byline_id, MAX(IfNull(published_at, ?)) AS last_used
    FROM article
    GROUP BY byline_id
}, undef, time());

Spot the bug? No, nor did I.