How to query most recent post for each author?

Question

You can write a SQL query to achieve this:

<?php

$sql = <<<SQL
SELECT
    p.ID,
    p.post_title,
    p.post_author
FROM {$GLOBALS['wpdb']->posts} p INNER JOIN (
    SELECT ID, post_title
        FROM {$GLOBALS['wpdb']->posts} ORDER BY post_date DESC
    ) s ON p.ID=s.ID
WHERE
    p.post_type="post"
AND
    p.post_status="publish"
GROUP BY
  p.post_author
SQL;

$rows = $GLOBALS['wpdb']->get_results( $sql );