Just now I am working with a problem where I need to update a column/field by appending something. I was in a bit trouble for a 2 mins as I was finding a solution for this. First thing came to my mind is

UPDATE `table_name` SET `field_name`=`field_name`+’appending string’ WHERE `field_name`=’xxx’;

I knew this won’t work in my case. It is suitable when I need to SUM up floating point. However, I simply need to append to current value. Within two mins I got the idea that worked 100%. It is:

UPDATE `table_name` SET `field_name`=concat(`field_name`, ‘ appending string’) WHERE `field_name`=’xxx’;

Cool!