Syntax
------

REGEXP_SUBSTR(subject,pattern)

Description
-----------

Returns the part of the string subject that matches the regular expression
pattern, or an empty string if pattern was not found.

The function follows the case sensitivity rules of the effective collation.
Matching is performed case insensitively for case insensitive collations, and
case sensitively for case sensitive collations and for binary data.

The collation case sensitivity can be overwritten using the (?i) and (?-i)
PCRE flags.

MariaDB uses the PCRE regular expression library for enhanced regular
expression performance, and REGEXP_SUBSTR was introduced as part of this
enhancement.

The default_regex_flags variable addresses the remaining compatibilities
between PCRE and the old regex library.

Examples
--------

SELECT REGEXP_SUBSTR('ab12cd','[0-9]+');
-> 12

SELECT REGEXP_SUBSTR(
 'See https://mariadb.org/en/foundation/ for details',
 'https?://[^/]*');
-> https://mariadb.org

SELECT REGEXP_SUBSTR('ABC','b');
-> B

SELECT REGEXP_SUBSTR('ABC' COLLATE utf8_bin,'b');
->

SELECT REGEXP_SUBSTR(BINARY'ABC','b');
->

SELECT REGEXP_SUBSTR('ABC','(?i)b');
-> B

SELECT REGEXP_SUBSTR('ABC' COLLATE utf8_bin,'(?+i)b');
-> B

URL: https://mariadb.com/kb/en/regexp_substr/