Whoops!
OK, so what’s wrong with this query?
UPDATE typhoon_posts SET post_date = '2005-05-11 11:13:00', post_date_gmt = '2005-05-12 06:13:00'
If you guessed no WHERE clause, you’re right! Whoops! It was one of those things that as soon as I hit enter, I knew I had fucked up big time. Luckily I had about a month old backup and I only had about 20 posts since then, which Google’s cache gratefully provided me the date and times on. Thank god for Google Cache. Note to self: need more regular backups.
Another note. MySQL 3.23 really sucks! No joins on update statements, no subqueries. It was a real bitch to fix this without those features!