Postgresql regexp_matches syntax not working as expected

Question

I use the Postgres regexp_matches function to extract numbers.

The regular expression I use is

4([\\s\\-\\/\\.]*?0){3}([\\s\\-\\/\\.]*?[         


        

Answer 1

The regexp_matches(string text, pattern text [, flags text]) function returns the captured values:

Return all captured substrings resulting from matching a POSIX regular expression against the string.

You may fix the expression using non-capturing groups:

SELECT unnest(regexp_matches('4-0001-1234 4.0001.12344  4-0-0-0-1-1234', '4(?:[\s/.-]*0){3}(?:[\s/.-]*[12])(?:[\s/.-]*\d){4}', 'g'));

See the online demo.

BTW, you do not need to escape - when it is at the start/end of the bracket expression, and there is no need to escape neither / nor . there. I also suggest removing {1} as a = a{1} in any regex supporting limiting quantifiers.