Below is a great MySQL query to do a table wide search and replace.

Its especially handy if you are moving your staging database to production and want to change the URLs.

UPDATE `wp_posts` SET `post_content` = REPLACE (  
`post_content`,  
'http://dev.johnburns87.com/',  
'http://www.johnburns87.com/');

UPDATE `wp_posts` SET `guid` = REPLACE (  
`guid`,  
'http://dev.johnburns87.com/',  
'http://www.johnburns87.com/');