Replacing, Updating, Changing text in WordPress fields is as easy as using the MySQL replace command. Here’s an example for updating the post_title field:
update wp_posts set post_title = REPLACE(post_title, 'Old', 'New') WHERE post_title LIKE '%Old%';
This will update all the columns that have the word ‘Old’ in their post_title field with the word ‘New’. A very easy way to update multiple columns in MySQL with one query string.