Reference to groups in a MySQL regex?
Solution 1:
(Old question, but top search result)
For MySQL 8:
SELECT REGEXP_REPLACE('stackoverflow','(.{5})(.*)','$2$1');
-- "overflowstack"
You can create capture groups with (), and you can refer to them using $1, $2, etc.
For MariaDB, capturing is done in REGEXP_REPLACE with \\1, \\2, etc. respectively.
Solution 2:
You can't, there is no way to reference regex capturing groups in MySql.