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我已将 Firebase 分析数据与 google BigQuery 集成，并且每天都会创建一个带有 DATE 标记的新表。

一个示例表是“projectID.com_dev_sambhav_ANDROID.app_events_20170821”

示例表如下所示

我的要求是获得 event_dim.name="notification_received" 所需输出的以下所需格式的结果

为了得到这个期望的输出，我执行下面的查询（standardSQL）

SELECT event.name
 (SELECT param.value.string_value FROM UNNEST(event_dim.params) AS param WHERE param.key="notification_title") as notification_title,
 (SELECT param.value.string_value FROM UNNEST(event_dim.params) AS param WHERE param.key="item_id") as item_id 
FROM `projectID.com_dev_sambhav_ANDROID.app_events_20*`, UNNEST(event_dim) as event  
WHERE event.name = "notification_received"

但我得到了这个错误

错误：每个函数参数都是一个表达式，而不是一个查询。要将查询用作表达式，查询必须用额外的括号括起来，以使其成为标量子查询表达式。

谁能帮我摆脱这个问题

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1 回答 1

1

问题是逗号和别名。此查询有效：

#standardSQL
WITH `projectID.com_dev_sambhav_ANDROID.app_events_2017` AS(
  SELECT ARRAY< STRUCT<date STRING, name STRING, params ARRAY< STRUCT<key STRING, value STRUCT<string_value STRING> > > > > [STRUCT('20170814' AS date, 'notification_received' AS name, [STRUCT('notification_title' AS key, STRUCT('Amazing Offers two' AS string_value) AS value ), 
                                                                                                                STRUCT('firebase_screen_class' AS key, STRUCT('RetailerHomeActivity' AS string_value) AS value),
                                                                                                                STRUCT('notification_id' AS key, STRUCT('12345' AS string_value) AS value),
                                                                                                                STRUCT('firebase_screen_id' AS key, STRUCT('app' AS string_value) AS value),
                                                                                                                STRUCT('item_id' AS key, STRUCT('DEMO-02' AS string_value) AS value),
                                                                                                                STRUCT('firebase_screen' AS key, STRUCT('My Order' AS string_value) AS value)] AS params)] event_dim
)

SELECT
 event.name,
 (SELECT param.value.string_value FROM UNNEST(event.params) AS param WHERE param.key="notification_title") as notification_title,
 (SELECT param.value.string_value FROM UNNEST(event.params) AS param WHERE param.key="item_id") as item_id 
FROM `projectID.com_dev_sambhav_ANDROID.app_events_20*`, UNNEST(event_dim) as event  
WHERE event.name = "notification_received"

如果您UNNEST使用该字段event_dim并调用它event，那么您应该在查询中使用此别名作为参考。

作为补充，这也是解决您的问题的另一种方法（这只是另一种可能性，因此您在使用 BigQuery 时掌握了更多技术）：

#standardSQL
SELECT
  (SELECT date FROM UNNEST(event_dim)) date,
  (SELECT params.value.string_value FROM UNNEST(event_dim) event, UNNEST(event.params) params WHERE event.name = 'notification_received' AND params.key = 'notification_title') AS notification_title,
  (SELECT params.value.string_value FROM UNNEST(event_dim) event, UNNEST(event.params) params WHERE event.name = 'notification_received' AND params.key = 'item_id') AS item_id
FROM `projectID.com_dev_sambhav_ANDROID.app_events_2017`
WHERE EXISTS(SELECT 1 FROM UNNEST(event_dim) WHERE name = 'notification_received')

在处理高达 TB 的数据时，您可能会发现此查询仍然执行得很好。

于 2017-08-23T10:19:16.270 回答