Return Only number from a string if it contains numbers

Question

For example,
string is abc123CD need to find out a method to read only numbers in the string
i.e.

  select a_postgres_function(\'a         


        

Answer 1

If you want to get all digit characters from the string (not just the first group), it is easier to remove all characters, which aren't a digit:

select regexp_replace('abc123CD45ef', '[^\d]+', '', 'g');

-- regexp_replace
-- --------------
--    '12345'