Create string from array

Question

I have a table in PostgreSQL that contains:

id   name   arrayofparents
1     First
2     Second      {1}
3     Second_Sec  {1,2}
4     Third       {1,2,3}
5          


        

Answer 1

you can combine muliple operations like generate_subscripts and array to get the result:

with mtab as (
      SELECT id, name, array_append(arrayofparents,id) as arrayofparents,
      generate_subscripts(array_append(arrayofparents, id), 1) AS p_id FROM tab where id=2
)
select distinct array_to_string(
  array(
    select tab.name from tab join mtab t on tab.id=t.arrayofparents[t.p_id]
  ), '->'
) ;

live example Sqlfiddle

or use outer join combined with any:

SELECT coalesce(string_agg(p.name, '->') || '->' || t.name, t.name) AS parentnames
FROM tab AS t
  LEFT JOIN tab AS p ON p.id = ANY(t.arrayofparents)
 where t.id =7 
GROUP BY t.id, t.name

live example Sqlfiddle