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

As per ntalbs's Answer

---

Wrap that query into a Function

create or replace function shownums(text) returns integer as 
$$
select (regexp_matches($1,'\d+'))[1]::int; 
$$
language sql;