update row without rewriting the data mysql query correct syntax

Question

I have the following and it is generating errors

SELECT * (CONCAT('asd, ') as userHiddenSomeId) 
FROM users

How the query should look like to append data inside the userHiddenSomeId rows?

Answer 1

Your error is caused by a wron sintax

assuming you want add the prefix asd the column my_column you concat should be

  SELECT *,  CONCAT('asd',  my_column  ) as userHiddenSomeId
  FROM users

for the update assuming you want update the column userHiddenSomeId adding a prefix to the previous value then you nedd the prefix asd the the column my_column you concat should be

  Update  user 
  set  userHiddenSomeId = CONCAT('asd',  userHiddenSomeId  )