If you need to update part of the strings in your database you can do so using this syntax.
This is specially useful when you want to fix some URLS stored in the database.
update TABLE_NAME set FIELD_NAME = replace(FIELD_NAME, ‘old string’, ‘replace with new string);
Remember, it will replace the part of the string. Example from WordPress
update wp_posts set guid = replace(guid, 'http://localhost:8888/abc/', 'http://abc.yourdomain.com/');
This will fix http://localhost:8888/abc/?p=123 into http://abc.yourdomain.com/?p=123.