Oracle SQL report generation without null

My query:

SELECT s.artist_id AS ArtistID,
       s.name AS Song,
       at.name AS artistname,
       a.name AS Albumname
  FROM album s
       LEFT OUTER JOIN song a ON s.id = a.album_id
       LEFT OUTER JOIN artist at ON at.id = s.artist_id;

null in song and album table

for above query after joining the tables there is null in report (demo result)

Actual result

A B     
1 2                                                        
3 

Expected result

A B                                   
1 2                                                  
3 *  

I want to print the above result in excel instead of null it should be replaced with any character. Could you pls help me how to do it?

One option is to use the NVL function, e.g.

nvl(a.name, '*') as albumname

Or, DECODE might help:

decode(a.name, null, '*', a.name) as albumname

Or CASE:

case when a.name is null then '*'
     else a.name
end as albumname