認沽值到普通數組

Question

我已經text[]回到我plv8{1,32}，我已經比較下面的JSON的裏面是什麼：

'{"title":"Televisão em cores" 
    , "answers":[{"weight":0, "weight2":1, "title":"Não tem"} 
      , {"weight":1, "weight2":2, "title":"1"} 
      , {"weight":2, "weight2":4, "title":"2"} 
      , {"weight":3, "weight2":8, "title":"3"} 
      , {"weight":4, "weight2":16, "title":"4 ou +"}]}' 

我怎樣才能得到所有的名字weight2並將它們轉換爲text[]？像{1,2,4,8,16}？

Answer 1

對於單個json值j了在Postgres 9.3：

SELECT ARRAY(SELECT json_array_elements(j->'answers')->>'weight2'); 

結果：

array 
{1,2,4,8,16} 

The manual has more.