BigQuery 如何获取 JSON 结构中的值的总和？答案

【问题标题】：BigQuery How to get the sum of values in a JSON struct?BigQuery 如何获取 JSON 结构中的值的总和？
【发布时间】：2017-11-30 16:36:56
【问题描述】：

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)

{"蓝色":1.0,"紫色":0.0,"黄色":1.0,"绿色":1.0}

我想看看是否有办法总结所有颜色的值。返回的意思：

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。

【问题讨论】：

标签： json google-bigquery bigquery-standard-sql

【解决方案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;

【讨论】：

完美工作。非常感谢！

【解决方案2】：

为了探索其他选择 -

以下是 BigQuery 标准 SQL

第一个例子是为每一行提取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

这会给你下面的结果

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，甚至可以通过可能过滤特定颜色来进一步扩展它 - 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（计算中不包括 color=blue）

id  total    
1   2.0  
2   6.0

【讨论】：

这个也很好用，谢谢你的回答，米哈伊尔！