StandardSQL BigQuery 值从 Array 中的键：值对到单独的列中。如何？

Question

我有一个 BigQuery 表，其中包含一个数组列，其中包含多个（1 到 4 个）键：值对，由管道“|”分隔。我想提取键：值对并添加额外的列，其中“键”作为列标题，“值”以及......以及值/条目。

但是，虽然有统一的“键”，但它们并非都以相同的顺序放置，因此按顺序拆分并不能安静地工作。我环顾四周并探索了“JSON_EXTRACT_SCALAR”和“UNNEST”（来自此问题/答案：fetch key value pairs from array objects in sql BigQuery），但无法获得理想的结果。我也探索过使用“OFFSET”，但不知道如何将它们放在一起。

这是数据字段（它们的数组）的样子：

Row campaignLabels  
1   Segment: Rivers Non-Brand | Strategy: All Else | Category: Non-Brand | CN:Pause_5-29-19
2   Segment: Rivers Non-Brand | Category: Non-Brand | Strategy: All Else | CN:Pause_5-29-19
3   Category: Upper Funnel | Strategy: All Else
4   Strategy: All Else | Segment: Rivers Brand | Category: Brand
5   Strategy: All Else | Category: Brand | Segment: Rivers Brand
6   Segment: Rivers Non-Brand | Category: Non-Brand | Strategy: All Else
7   Strategy: All Else | Segment: Viking Other Brand | Category: Brand
8   Strategy: All Else | Category: Brand | Segment: Rivers Brand
9   Strategy: All Else | Category: Brand | Segment: Rivers Brand
10  Strategy: All Else | Category: Brand | Segment: Viking Other Brand

理想的输出是查询同一个表，拉取某些列，并添加具有“策略”、“类别”和“段”的列作为列标签，并将值作为返回值。

救命！

一些尝试给了我部分但不是所需的结果：

SELECT 
  DISTINCT(SUBSTR(Part1, 10)) AS Strategy
FROM (
  SELECT
    Labels[OFFSET(0)] AS Part1,
    Labels[OFFSET(1)] AS Part2,
    Labels[SAFE_OFFSET(2)] AS Part3,
    Labels[SAFE_OFFSET(3)] AS Part4
  FROM (
    SELECT
      SPLIT(campaignLabels,"| ") AS Labels
    FROM
      `table_A` )
  )
WHERE Part1 LIKE "Strategy:%"

Answer 1

以下是 BigQuery 标准 SQL

#standardSQL
select campaignLabels, 
  ( select as struct
      max(if(key = 'Segment', value, null)) as Segment,
      max(if(key = 'Strategy', value, null)) as Strategy,
      max(if(key = 'Category', value, null)) as Category
    from (
      select as struct kv[offset(0)] as key, trim(kv[offset(1)]) as value
      from t.labels label, 
      unnest([struct(split(label, ':') as kv)])
    )
  ).*
from `project.dataset.table`, 
unnest([struct(split(campaignLabels, ' | ') as labels)]) t    

如果应用到我们的问题中的样本数据 - 输出是