not displaying 'none' instead of a 0

Question

Right now my query is giving me a 0 when I count the enrolled date. How could I have a row show me 'none' result instead of a 0.

what I am missing here ?

COALESCE(TO_CHAR(SUM(ENROLLMENTS)),'none') ENROLLMENTS

this is what I have

SELECT lt.STUDENT_ID,lt.FIRST_NAME, lt.LAST_NAME,COALESCE(TO_CHAR(SUM(ENROLLMENTS)),'none') ENROLLMENTS
FROM STUDENT lt
LEFT OUTER JOIN
(SELECT s.STUDENT_ID, z.COURSE_NO,COUNT(e.ENROLL_DATE) AS ENROLLMENTS
FROM   STUDENT s
LEFT   JOIN ENROLLMENT e ON s.STUDENT_ID = e.STUDENT_ID
LEFT   JOIN SECTION z ON e.SECTION_ID = z.SECTION_ID
WHERE  s.PHONE LIKE '702%'
GROUP  BY s.STUDENT_ID, z.COURSE_NO) rt
ON lt.STUDENT_ID = rt.STUDENT_ID
WHERE lt.PHONE LIKE '702%'
GROUP BY lt.STUDENT_ID,lt.FIRST_NAME, lt.LAST_NAME,ENROLLMENTS
ORDER BY lt.LAST_NAME,lt.FIRST_NAME;

instead of having results

STUDENT_ID FIRST_NAME                LAST_NAME                 ENROLLED
---------- ------------------------- ------------------------- -----------
       253 Walter                    Boremmann                     1 
       396 James E.                  Norman                        0 
etc

I'd like to have it like this

STUDENT_ID FIRST_NAME                LAST_NAME                 ENROLLED
---------- ------------------------- ------------------------- -----------
       253 Walter                    Boremmann                     1 
       396 James E.                  Norman                        none
etc

Answer 1

I think you need a CASE statement because TO_CHAR is returning "0":

(CASE WHEN SUM(ENROLLMENTS)=0 THEN 'none' ELSE SUM(ENROLLMENTS) END) ENROLLMENTS