下面是bigquery标准sql

# standardSQL

SELECT (
  SELECT STRING_AGG(JSON_EXTRACT_SCALAR(answer, '$.answer'), ' ,') 
  FROM UNNEST(JSON_EXTRACT_ARRAY(json_string)) answer
  ) AS answers 
FROM `project.dataset.table`

您可以使用下面的示例中的问题中的示例数据来测试、播放上述内容

# standardSQL

WITH `project.dataset.table` AS (
  SELECT '[{"answer":"europe-austria-swiss","text":"Österreich, Schweiz"},{"answer":"europe-italy","text":"Italien"},{"answer":"europe-france","text":"Frankreich"}]' json_string
)
SELECT (
  SELECT STRING_AGG(JSON_EXTRACT_SCALAR(answer, '$.answer'), ' ,') 
  FROM UNNEST(JSON_EXTRACT_ARRAY(json_string)) answer
  ) AS answers 
FROM `project.dataset.table`

有结果的

Row answers
1   europe-austria-swiss ,europe-italy ,europe-france

我想我知道发生了什么事（如果我错了，请纠正我）。
我最好的猜测是你在尝试这样的事情：

SELECT JSON_EXTRACT(json_text, "$.answer") AS answers
FROM UNNEST([
'{"answer":"europe-austria-swiss","text":"Österreich, Schweiz"},{"answer":"europe-italy","text":"Italien"},{"answer":"europe-france","text":"Frankreich"}'
]) as json_text

这将返回：

"europe-austria-swiss"

但是，如果您为类似的内容更改基础数据（每行作为一个json字符串对象），应该可以解决这个问题：

SELECT JSON_EXTRACT(json_text, "$.answer") AS answers
FROM UNNEST([
'{"answer":"europe-austria-swiss","text":"Österreich, Schweiz"}',
'{"answer":"europe-italy","text":"Italien"}',
'{"answer":"europe-france","text":"Frankreich"}'
]) as json_text

结果：

"europe-austria-swiss"
"europe-italy"
"europe-france"

希望这有帮助！