bigquery:string\u value`vs`string有什么区别`

这可能是一个具体的案例data.to_值记录已定义。 不看一些样本数据就很难说。 下面的例子来自Firebase,在这里您可以看到string_value、int_value、double_value等,在本例中它们只是列名。

SELECT 
  MAX(if(param.key = "value", param.value.int_value, NULL)) AS score,
  MAX(if(param.key = "board", param.value.string_value, NULL)) AS board_type
FROM (
  SELECT event_name, event_timestamp, user_pseudo_id, param
  FROM `firebase-public-project.analytics_153293282.events_20181003`,
  UNNEST(event_params) AS param
  WHERE event_name = "level_complete_quickplay" 
  AND (param.key = "value" OR param.key = "board")
) 
GROUP BY user_pseudo_id, event_timestamp