Question

我正在迁移到BigQuery中的新SQL语法，因为它似乎更灵活。但是，在访问customDimensions中的字段时，我有点卡住了。我写的东西很简单：

SELECT 
  cd.customDimensions.index,
  cd.customDimensions.value
FROM `xxxxx.ga_sessions_20170312`, unnest(hits) cd
limit 100

但是我收到了错误

Error: Cannot access field index on a value with type ARRAY<STRUCT<index INT64, value STRING>>

然而，如果我运行这样的东西完全正常：

    SELECT 
        date,
        SUM((SELECT SUM(latencyTracking.pageLoadTime) FROM UNNEST(hits))) pageLoadTime,
        SUM((SELECT SUM(latencyTracking.serverResponseTime) FROM UNNEST(hits))) serverResponseTime
   FROM `xxxxxx.ga_sessions_20170312`
    group by 1

在查询customDimensions时是否有一些不同的逻辑？

Answer 1

如果打算以展平形式检索所有自定义维度，请同时加入UNNEST(customDimensions)：

#standardSQL
SELECT 
  cd.index,
  cd.value
FROM `xxxxx.ga_sessions_20170312`,
  unnest(hits) hit,
  unnest(hit.customDimensions) cd
limit 100;

Answer 2

SELECT
fullvisitorid,
( SELECT MAX(IF(index=1,value, NULL))FROM UNNEST(hits.customDimensions)) AS CustomDimension1,
( SELECT MAX(IF(index=2,value, NULL))FROM UNNEST(hits.customDimensions)) AS CustomDimension2
FROM
  `XXXXXXX`, unnest(hits) as hits

BigQuery使用新的SQL语法访问CustomDimensions

2 个答案: