Your solution is going to be a combination of an update
and modifying the result using string literals
and variables in MySQL.
UPDATE <table_name>
SET col_name1={expr1|DEFAULT} [, col_name2={expr2|DEFAULT}] ...
[WHERE where_condition]
You are going to need to figure out how to “set” your column to the current value + a string literal. Your question does look a little confusing and its hard to tell if you actually need a variable or not, or if you are just appending something to the current value…
solved Adding a variable to current value of field in MySQL [closed]