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

---

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

Answer 2

You don't need regex; you can use SUBSTRING_INDEX to extract everything after the hyphen and concatenate 4- to that:

UPDATE myTable
SET col1 = CONCAT('4-', SUBSTRING_INDEX(col1, '-', -1))

Demo on dbfiddle

This will work regardless of the number of characters after the hyphen.

Answer 3

Looking to your pattern seem you could avoid regexp

update myTable  
set col1  = concat('4-', right(col1,8))

or

update myTable  
set col1  = concat('4', right(col1,9))

Answer 4

Try this:

UPDATE testing SET val=REPLACE(val,SUBSTRING(val,1,LOCATE('-',val)),'4-');

Fiddle here :https://www.db-fiddle.com/f/4mU5ctLh8NB9iKSKZF9Ue2/2

Using LOCATE to find '-' position then use SUBSTRING to get only the front part of the '-'.