I have a table in MySQL 8. In a varchar column, I want to replace long substrings by another substrings. I can find those rows using this regex:

SELECT notetext FROM mytable WHERE notetext REGEXP '[a-zA-Z0-9_.:/-]{45,}';

This Regex searches for all rows that has substrings with length>45. However, I cannot figure out how to replace the matched substrings by a replacement substring. I want to do something like this:

  update mytable set notetext = replace(notetext,** regex match ***,  'replacement text') WHERE notetext REGEXP '[a-zA-Z0-9_.:/-]{45,}';