Why MySql query update with guid don't affect rows?

I have a MySql query update:

UPDATE wp_posts SET  guid = REPLACE (guid, 'http://oldcomain.com/', 'http://ift.tt/1bP7JLx') WHERE post_type = 'attachment';

I'm using it on wordpress domain, inside amazon rds database, i'm updating it via MySQL Workbench and get there results:

0row(s) affected Rows matched: 24103 Changed: 0 Warning: 0

As you can see it finds rows that i need, but it does not update, i'm trying update all my wordpress media that is on wordpress to my cdn amazon s3 url.

Update: Also tried:

UPDATE wp_posts SET post_content = REPLACE (post_content, 'olddocmain.com', 'newcdndomain.com') WHERE post_type = 'attachment';

Doesn't work ether.