Can MySQL replace multiple characters?

Question

I\'m trying to replace a bunch of characters in a MySQL field. I know the REPLACE function but that only replaces one string at a time. I can\'t see any appropriate function

Answer 1

REPLACE does a good simple job of replacing characters or phrases everywhere they appear in a string. But when cleansing punctuation you may need to look for patterns - e.g. a sequence of whitespace or characters at particular parts of the text, e.g. in the middle of a word or after a full stop. If that's the case, a regular expression replace function would be much more powerful.

---

UPDATE: If using MySQL version 8+, a REGEXP_REPLACE function is provided and can be invoked as follows:

SELECT txt,
       REGEXP_REPLACE(REPLACE(txt, ' ', '-'),
                      '[^a-zA-Z0-9-]+',
                      '') AS `reg_replaced`
FROM test;

See this DB Fiddle online demo.

---

PREVIOUS ANSWER - only read on if using a version of MySQL before version 8: .

The bad news is MySQL doesn't provide such a thing but the good news is it's possible to provide a workaround - see this blog post.

Can I replace or delete multiple strings at once? For example I need to replace spaces with dashes and remove other punctuation.

The above can be achieved with a combination of the regular expression replacer and the standard REPLACE function. It can be seen in action in this online Rextester demo.

SQL (excluding the function code for brevity):

SELECT txt,
       reg_replace(REPLACE(txt, ' ', '-'),
                   '[^a-zA-Z0-9-]+',
                   '',
                   TRUE,
                   0,
                   0
                   ) AS `reg_replaced`
FROM test;