How to replace a substring in a Mysql table with a randomly selected emoji from a list?

Question

MySQL

Good day!
There is a problem, in the database, when transferring, emoji were rubbed and changed to a question mark "?", there were emoji of the form: .
How to correctly compose a mysql query to replace a character ? in the field of the table on a randomly selected emoji from the list?

UPDATE `modx_site_content` SET `longtitle` = REPLACE(`longtitle`, ' ? ', '  ');

With one character, everything is clear, but with a random question from the list, please help.

Habr overwrites emoji in this regard, imagine that emoji corresponds to any letter of the alphabet, for example a, b, c, d, e, and you need to replace the question mark with spaces on the left and right with a letter from the list above

Answer 1

UPDATE 
`modx_site_content` t1
SET t1.`longtitle` = REPLACE(`longtitle`, ' ? ', 
(
select t2.*
from 
(
  select 'a'
  union
  select 'b'
  union
  select 'c'
) t2
order by rand() limit 1
)
);

Answer 2

changed to a question mark "?"

Because at some stage of the transfer, the characters were recoded into a different encoding.