Create a documents table:

CREATE table documents (objectid char(16), objectname char(80))
INSERT into documents (objectid, objectname) 
values ('456', 'Test document'), ('123', 'Folder'), ('121', 'Upper folder'), ('120', 'Parent')

Create a relationships table:

CREATE table relationships (objectid char(16), parent char(16))
INSERT into relationships (objectid, parent) 
values ('121','120'), ('123', '121'), ('456','123')

I am trying to use a SQL query to return the top relationship of each document like so:
objectid | topcontainer
—— | ——
120 | 120
121 | 120
123 | 120
456 | 120

I tried to use the following query, but it is not working. Not sure why but it terminates.

WITH c AS 
(
    SELECT d.objectid, r.parent, r.parent AS topcontainer
    FROM documents d
    JOIN relationships r ON d.objectid = r.objectid

    UNION ALL 

    SELECT 
        t.objectid, t.parent, c.topcontainer 
    FROM   
        relationships AS t
    JOIN c ON t.parent = c.parent 
) 
SELECT objectid, topcontainer 
FROM c 
ORDER BY c.objectid