gistfile1.txt

WITH j_1 AS (
  SELECT subject
  FROM wb_v_latest_triples a
  WHERE 
  a.predicate = 'type' AND a.obj_value = 'http://indx.ecs.soton.ac.uk/ontology/root-box/#server'
),
WITH j_2 AS (
  SELECT subject
  FROM wb_v_latest_triples a
  WHERE 
  a.predicate = 'box'
)

SELECT DISTINCT
j.triple_order, 
j.subject, 
j.predicate, 
j.obj_value, 
j.obj_type, 
j.obj_lang, 
j.obj_datatype 
FROM wb_v_latest_triples as j
  JOIN j_1 USING subject
  JOIN j_2 USING subject
  JOIN wb_v_latest_triples AS j_3 ON (j.subject = j_3.subject)  
WHERE
 j_2.obj_value = j_3.subject -- concerned about the j_2.obj_value = j_3.subject ...