The following code is how you would mass-update a single field in a MySQL table with a string prepended and appended to the field’s existing value.

UPDATE `table` SET `field` = CONCAT('prepend',`field`,'append') WHERE 1

We used this method update all the records in an osCommerce store to point to images (uploaded via FTP) that were named after the product’s model number. The code we used is displayed below.

UPDATE `products` SET `products_image` = CONCAT('products/',products_model,'.jpg') WHERE 1

I hope this helps some of you MySQL users out there. If all else fails, read the DOCs