BigQuery 如何获取 JSON 结构中值的总和？

Question

我有以下查询

SELECT 
    JSON_EXTRACT(json, '$.Weights') as weight 
from 
(select '{"Weights":{"blue":1.0,"purple":0.0,"yellow":1.0,"green":1.0}}' as json)

其中 returns :

{"blue":1.0,"purple":0.0,"yellow":1.0,"green":1.0}

我想看看有没有办法求和所有颜色的值。意思是 return:

3.0

我一直在尝试使用 split 和 unnest 函数但没有成功，有什么建议吗？谢谢

Answer 1

这里是一个使用 REGEXP_EXTRACT_ALL 的例子：

WITH T AS (
  SELECT '{"Weights":{"blue":1.0,"purple":0.0,"yellow":1.0,"green":1.0}}' AS json
)
SELECT
  (
    SELECT SUM(CAST(val AS FLOAT64))
    FROM UNNEST(
      REGEXP_EXTRACT_ALL(
        JSON_EXTRACT(json, '$.Weights'),
        r':([^,}]+)')
    ) AS val
  )
FROM T;

Answer 2

为了探索其他选择 -

以下适用于 BigQuery 标准 SQL

第一个示例是为每一行提取 key:value 对

#standardSQL
WITH `project.dataset.yourTbale` AS (
  SELECT 1 AS id, '{"Weights":{"blue":1.0,"purple":0.0,"yellow":1.0,"green":1.0}}' AS json 
  UNION ALL SELECT 2, '{"Weights":{"blue":1.0,"red":2.0,"yellow":1.0,"orange":3.0}}'
)
SELECT id,
  REPLACE(SPLIT(pair, ':')[OFFSET (0)], '"', '') color, 
  SAFE_CAST(SPLIT(pair, ':')[OFFSET (1)] AS FLOAT64) value
FROM `project.dataset.yourTbale`, 
UNNEST(SPLIT(REGEXP_REPLACE(JSON_EXTRACT(json, '$.Weights'), r'{|}', ''))) pair

这给你下面的结果

id  color   value    
1   blue    1.0  
1   purple  0.0  
1   yellow  1.0  
1   green   1.0  
2   blue    1.0  
2   red     2.0  
2   yellow  1.0  
2   orange  3.0

所以现在很容易将上面的内容扩展到 if there is a way to sum up all the values of the colors 的原始问题，甚至可以通过对特定颜色进行潜在过滤来进一步扩展它 - 请参见下面的示例

#standardSQL
WITH `project.dataset.yourTbale` AS (
  SELECT 1 AS id, '{"Weights":{"blue":1.0,"purple":0.0,"yellow":1.0,"green":1.0}}' AS json 
  UNION ALL SELECT 2, '{"Weights":{"blue":1.0,"red":2.0,"yellow":1.0,"orange":3.0}}'
)
SELECT id,
  SUM(SAFE_CAST(SPLIT(pair, ':')[OFFSET (1)] AS FLOAT64)) AS total
FROM `project.dataset.yourTbale`, 
UNNEST(SPLIT(REGEXP_REPLACE(JSON_EXTRACT(json, '$.Weights'), r'{|}', ''))) pair
WHERE REPLACE(SPLIT(pair, ':')[OFFSET (0)], '"', '') != 'blue'
GROUP BY id

结果如下（从计算中排除了 color=blue）

id  total    
1   2.0  
2   6.0

BigQuery 如何获取 JSON 结构中值的总和？

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