如何在 bigquery 中使用 group_concat 生成 json 字符串？

Posted 2023-03-25

【中文标题】如何在 bigquery 中使用 group_concat 生成 json 字符串？

【英文标题】：How can I generate json string with group_concat in bigquery?

【发布时间】：2017-12-15 03:53:57

【问题描述】：

我有一张桌子：

user   device   minutes
====   ======   =======
ben    phone    1.9
ben    tablet   2.3
anna   phone    1.6

我想将设备使用打包成一个json字符串，用户喜欢：

user   json
====   =====
ben    "phone":1.9, "tablet":2.3
anna   "phone":1.6, "tablet":2.3

如何在 bigquery 中执行此操作？

【参考方案1】：

以下是 BigQuery 标准 SQL 的版本

#standardSQL
WITH `yourproject.yourdataset.yourtable` AS (
  SELECT 'ben' user, 'phone' device, 1.9 minutes UNION ALL
  SELECT 'ben', 'tablet', 2.3 UNION ALL
  SELECT 'anna', 'phone', 1.6 
)
SELECT 
  user, 
  CONCAT('', STRING_AGG(CONCAT('"',device, '":', CAST(minutes AS STRING))), '') json,
  ROUND(SUM(IF(device='tablet',minutes,0)),2) tablet_minutes
FROM `yourproject.yourdataset.yourtable`
GROUP BY user 

输出如下

user    json                        tablet_minutes   
ben     "phone":1.9,"tablet":2.3  2.3  
anna    "phone":1.6               0.0  

【参考方案2】：

使用 BigQuery 旧版 SQL

# legacySQL
SELECT
  user,
  json,
  JSON_EXTRACT_SCALAR(json, '$.tablet') AS tablet_minutes
FROM (
  SELECT
    user,
    CONCAT('', GROUP_CONCAT_UNQUOTED(CONCAT('"', device,'":', minutes)), '') AS json,
  FROM 
    (SELECT 'ben' user, 'phone' device, '1.9' minutes),
    (SELECT 'ben' user, 'tablet' device, '2.3' minutes),
    (SELECT 'anna' user, 'phone' device, '1.6' minutes),
  GROUP BY
    user)

使用标准 SQL（感谢 Mikhail）

# standardSQL
WITH `yourproject.yourdataset.yourtable` AS (
  SELECT 'ben' user, 'phone' device, 1.9 minutes UNION ALL
  SELECT 'ben', 'tablet', 2.3 UNION ALL
  SELECT 'anna', 'phone', 1.6 
)
SELECT 
  user, 
  CONCAT('', STRING_AGG(CONCAT('"',device, '":', CAST(minutes AS STRING))), '') json,
  ROUND(SUM(IF(device='tablet',minutes,0)),2) tablet_minutes
FROM `yourproject.yourdataset.yourtable`
GROUP BY user 

两个输出

user    json                        tablet_minutes
====    ====                        ==============   
ben     "phone":1.9,"tablet":2.3  2.3  
anna    "phone":1.6               0.0