How to replace a regex pattern in MySQL

Question

I have a table called myTable which has a column called col1. This column contains data in this format: (1 or 2 digits)(hyphen)(8 digits).

I wa

Answer 1

SELECT CONCAT( @new_prefix, SUBSTRING(old_value FROM LOCATE('-', old_value)) ) AS new_value

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UPDATE sourcetable
SET fieldname = CONCAT( '4', SUBSTRING(fieldname FROM LOCATE('-', fieldname)) )
WHERE LOCATE('-', fieldname)
/* AND another conditions */