Weird behaviour with escape of REGEX in MySQL -

Weird behaviour with escape of REGEX in MySQL -

can please explain me behaviour?

mysql> select *, ('http://www.thisisatest.es/?utm_source=xxxx&utm_term=&utm_campaign=xxxx&utm_medium=xxxx' regexp rule) r containers_rules; +---------------------------------------------------------------------------------------+------+ | rule | r | +---------------------------------------------------------------------------------------+------+ | ^http://www.thisisatest.es/\\?utm_source | 0 | | ^http://www.thisisatest.es/\?utm_source | 1 | +---------------------------------------------------------------------------------------+------+ 5 rows in set (0.01 sec) mysql> select 'http://www.thisisatest.es/?utm_source=xxxx&utm_term=&utm_campaign=xxxx&utm_medium=xxxx' regexp '^http://www.thisisatest.es/\\?utm_source' r; +---+ | r | +---+ | 1 | +---+ 1 row in set (0.00 sec)

i don't understand why manual regex comparing needs 2 "\" , dynamic regex comparing 1 "\" or won't work?

i bit lost...

the result set you're seeing shows column values (i.e. without additional escape characters).

however, string literal does require additional backslash; example, insert statement sec row have been:

insert ... values ('^http://www.thisisatest.es/\\?utm_source')

and matches manual query.

mysql regex