Question

I am trying to replace two dots following each other with Null.

SQL> select regexp_replace('..','[^\.]+\.','Null') from dual;

produces:

RE
--
..

whereas I want:

RE
--
Null

How do I achieve this using Regex?

Answer 1

Try the following:

SELECT regexp_replace( '..', '\.{2}', 'Null' ) FROM dual;

Your example is using the ^ symbol for negation (“do not match a .“), which I’m not sure is your intention. If you are instead wanting to match .. only at the beginning of a string, use ^ as follows:

SELECT regexp_replace( '..', '^\.{2}', 'Null' ) FROM dual;