oracle query data containing case

Query contains all data in lowercase:

select idno from user_info where regexp_like(idno,'[[:lower:]]');

 select idno from user_info where regexp_like(idno,'[a-z]');

 

The query contains all data in uppercase:

select idno from user_info where regexp_like(idno,'[[:upper:]]');

 select idno from user_info where regexp_like(idno,'[A-Z]');