PHP function to escape MySQL regexp syntax

Question

I'm looking for something similar to preg_quote, but for the MySQL regexp syntax.

Any ideas?

Answer 1

MySQL regexps are the ‘extended’ POSIX variant (ERE), available in PHP as the deprecated ereg_ functions.

Unfortunately there is no ereg_quote in PHP, however PCRE's special characters are a superset of ERE's special characters, and backslash-escaping a non-special punctuation character doesn't harm it, so you can get away with using preg_quote safely.

(Naturally you will need parameterised queries or mysql_real_escape_string after that quoting, to stop the backslashes being misinterpreted as MySQL's non-ANSI-standard string literal escapes.)

Answer 2

Sadly, PHP's preg_quote() messes up MySQL REGEXP by escaping a colon sign (:) which MySQL's REGEXP does not understand

Answer 3

There's no native MySQL function for that. You might just need to use preg_quote before passing the regular expression to the MySQL query.

Answer 4

Try this: (PHP)

    $tags="test'*\\\r blue";
    $tags=mysql_real_escape_string($tags);
    $tags=preg_replace('/([.*?+\[\]{}^$|(\)])/','\\\\\1',$tags);
    $tags=preg_replace('/(\\\[.*?+\[\]{}^$|(\)\\\])/','\\\\\1',$tags);

Answer 5

Thank @bobince's good answer. But it has a problem if you need to use mysql_real_escape_string after quoting, that I mentioned it in a comment.

Actually preg_quote and mysql_real_escape_string have overlap and it makes this problem! mysql_real_escape_string must not escape \ in this case. So I suggest:

function regexpEscape(/*string*/ $input) { // Uncomment `string` for PHP 7.0+
    return addcslashes(preg_quote($input), "\0'\"\n\r\x1A"); // charlist = All characters that escape by real_escape_string except backslash
}

(For charlist see: http://php.net/manual/en/mysqli.real-escape-string.php)

I know this is not an ideal way, but couldn't find a better way.