从BigQuery中的JSON数组中提取值

我试图从JSON数组中提取值，如下所示

  with `project.dataset.table` as (
  select '{"fruit":[{"apples":"5","oranges":"10","pear":"20"},
                    {"apples":"5","oranges":"4"},
                    {"apples":"5","oranges":"9","pear":"40"}]}' as json union all
  select '{"fruit":[{"lettuce":"7","kale": "8"}]}' 
)

select json, if(regexp_contains(json, '"apples":"5"'), (SELECT 
ARRAY_AGG(json_extract_scalar(arr, '$.oranges') ignore nulls)
from 
UNNEST(json_extract_ARRAY(json, '$.fruit')) as arr ), null) as oranges,
if(regexp_contains(json, '"apples":"5"'), (SELECT 
ARRAY_AGG(json_extract_scalar(arr, '$.pear') ignore nulls)
from 
UNNEST(json_extract_ARRAY(json, '$.fruit')) as arr ), null) as pear,
from `project.dataset.table` 

它给出如下输出

我期待像这样的输出

json 橘子 梨 {“水果”：[{“苹果”：“5”，“桔子”：“10”，“梨”：“20”}，{“苹果”：“5”，“桔子”：“4”}，{“苹果”：“5”，“桔子”：“9”，“梨”：“40”} 10 20 4. 无效的 9 40 {“水果”：[{“莴苣”：“7”，“羽衣甘蓝”：“8”}]}。 无效的 无效的 当与

如果最终查询结果中的数组包含 空元素

您可以尝试使用如下字符串

'null'

：

with `project.dataset.table` as (
  select '{"fruit":[{"apples":"5","oranges":"10","pear":"20"},{"apples":"5","oranges":"4"},{"apples":"5","oranges":"9","pear":"40"}]}' as json union all
  select '{"fruit":[{"lettuce":"7","kale": "8"}]}' 
)
select 
  json,
  if( regexp_contains(json, '"apples":"5"'),
    (SELECT ARRAY_AGG(ifnull(json_extract_scalar(arr, '$.oranges'), 'null')) from UNNEST(json_extract_ARRAY(json, '$.fruit')) as arr ),
    ['null']
  ) as oranges,
  if( regexp_contains(json, '"apples":"5"'),
    (SELECT ARRAY_AGG(ifnull(json_extract_scalar(arr, '$.pear'), 'null')) from UNNEST(json_extract_ARRAY(json, '$.fruit')) as arr ),
    ['null']
  ) as pear,
from `project.dataset.table`

---

考虑以下方法，更明确地对齐各个条目

select json, 
  array(
    select 
      if(
        json_extract_scalar(val, '$.apples') = '5',
        struct(
          json_extract_scalar(val, '$.oranges') as oranges,
          json_extract_scalar(val, '$.pear') as pear
        ),
        struct(null, null)
      )
    from t.arr val
  ) fruits
from `project.dataset.table`, 
unnest([struct(json_extract_array(json, '$.fruit') as arr)]) t      

与两个数组相比，它的详细程度更低，并将结果作为重复记录输出
如果应用于问题中的样本数据，则输出为

如果您真的需要将输出保持为单独的列，请使用下面的命令

select json, 
  array(
    select 
      if(
        json_extract_scalar(val, '$.apples') = '5',
        ifnull(json_extract_scalar(val, '$.oranges'), '0'),
        '0'
      )
    from t.arr val
  ) as oranges,
  array(
    select 
      if(
        json_extract_scalar(val, '$.apples') = '5',
        ifnull(json_extract_scalar(val, '$.pear'), '0'),
        '0'
      )
    from t.arr val
  ) as pear
from `project.dataset.table`, 
unnest([struct(json_extract_array(json, '$.fruit') as arr)]) t       

有输出

---

谢谢你的回答：）谢谢你的帮助：）这对我很有效！