Complex mysql query. Return as multiple rows as apposed to single row

Question

I currently have the following SQL query wich retrieves a record from a table and also it's parents and grandparent. The only issue I have is that it's returned as a single record. I would like it return as multiple rows, as it's stored in the database.

Current structure:

comment_id | parent_comment_id
    1              3
    2              7
    3              5
    7              11

SQL:

SELECT p3.comment_id as `Grandparent`, p2.comment_id as `Parent`, p1.comment_id as `Child`
FROM comments p1
LEFT JOIN comments p2 on p1.comment_id = p2.parent_comment_id
LEFT JOIN comments p3 on p2.parent_comment_id = p3.comment_id
WHERE p1.comment_id = 1

Current Output (single row):

Grandparent | Parent | Child  
     5          3        1

Desired Output (separate rows):

comment_id
     5
     3
     1

I am editing some existing mysql code, I do not have the option to convert everything to mysqli or pdo at the moment.

Answer 1

try this:

select comment_id from cm where comment_id = 1
union 
select parent_comment_id from cm where comment_id =1
union
select g.parent_comment_id from cm g
join cm p
on p.parent_comment_id = g.comment_id
where p.comment_id = 1;

please verify the logic and make sure it gives you the correct result.

Demo: SQLFiddle