Presto-提取數組中的鍵

Question

我有這個樣本數據（來自雅典娜）

 SELECT DISTINCT m.key
  FROM (VALUES JSON '{"name":"project1","completed":false}', JSON '{"name":"project1","completed":false}',JSON '{"name":"project1","completed":false}')
     example_table(json_column)
 CROSS JOIN UNNEST (map_keys(CAST(json_column AS map<varchar,json>))) AS m(key);

 WITH dataset AS (
  SELECT '{"name": "Susan Smith",
           "org": "engineering",
           "projects": [{"name":"project1", "completed":false},
           {"name":"project2", "completed":true}]}'
    AS blob
)
select * from dataset

這將生成以下輸出。

{"name": "Susan Smith", "org": "engineering", "projects": [{"name":"project1", "completed":false}, {"name":"project2", "completed":true}]}

我想從輸出中提取Key。

預期產量：

output
------
name
org
projects

有人可以幫忙嗎？

更新：

使用正確的JSON編輯了此問題。

Answer 1

根據評論中的討論，

map_keys(CAST(json_column AS map<varchar,json>))

需要替換為

map_keys(CAST(CAST(json_column AS JSON) AS map<varchar,json>))