Oracle regular expression regexp_like
What do you expect this query to do?

regexp_like is a regular expression version of the LIKE statement so it makes sense to use it in the same sorts of places that you would use a LIKE.  You wouldn't try to directly SELECT the result of a LIKE statement.  You could, however, embed the regexp_like in a case statement.  For example

SQL&gt; ed
Wrote file afiedt.buf

  1  select (case when regexp_like( 'https://www.hotmail.com' ,'(f|ht)tps?:')
  2               then 'true'
  3               else 'false'
  4           end) does_it_match
  5*   from dual
SQL&gt; /

DOES_
-----
true


regexp_like is a function that returns a boolean.  Oracle SQL, however, does not support the boolean data type so you cannot directly SELECT the result of the function just like you couldn't SELECT a function you write that returns a boolean.