Bigquery标准方言REGEXP_REPLACE输入类型

Question

我正在使用本教程使用GDELT数据库探索Google Biguery的功能，但是sql方言处于“传统”状态，我想使用标准方言。

在传统方言中：

SELECT
  theme,
  COUNT(*) AS count
FROM (
  SELECT
    REGEXP_REPLACE(SPLIT(V2Themes,';'), r',.*',"") theme
from [gdelt-bq:gdeltv2.gkg]
where DATE>20150302000000 and DATE < 20150304000000 and V2Persons like '%Netanyahu%'
)
group by theme
ORDER BY 2 DESC
LIMIT 300

当我尝试翻译成标准方言时：

SELECT
  theme,
  COUNT(*) AS count
FROM (
  SELECT
    REGEXP_REPLACE(SPLIT(V2Themes,';') , r',.*', " ") AS theme
    FROM
      `gdelt-bq.gdeltv2.gkg`
    WHERE
      DATE>20150302000000
      AND DATE < 20150304000000
      AND V2Persons LIKE '%Netanyahu%' )
  GROUP BY
    theme
  ORDER BY
    2 DESC
  LIMIT
    300

它会引发以下错误：

No matching signature for function REGEXP_REPLACE for argument types: ARRAY<STRING>, STRING, STRING. Supported signatures: REGEXP_REPLACE(STRING, STRING, STRING); REGEXP_REPLACE(BYTES, BYTES, BYTES) at [6:5]

看来我必须将SPLIT（）操作的结果转换为字符串。我该怎么做呢？

更新：我找到一个讲解不必要的操作的演讲：

SELECT
  COUNT(*),
  REGEXP_REPLACE(themes,",.*","") AS theme
FROM
  `gdelt-bq.gdeltv2.gkg_partitioned`,
  UNNEST( SPLIT(V2Themes,";") ) AS themes
WHERE
  _PARTITIONTIME >= "2018-08-09 00:00:00"
  AND _PARTITIONTIME < "2018-08-10 00:00:00"
  AND V2Persons LIKE '%Netanyahu%'
GROUP BY
  theme
ORDER BY
  2 DESC
LIMIT
  100

Answer 1

首先展平数组：

SELECT
  REGEXP_REPLACE(theme , r',.*', " ") AS theme,
  COUNT(*) AS count
FROM
  `gdelt-bq.gdeltv2.gkg`,
  UNNEST(SPLIT(V2Themes,';')) AS theme
WHERE
  DATE>20150302000000
  AND DATE < 20150304000000
  AND V2Persons LIKE '%Netanyahu%' 
GROUP BY
  theme
ORDER BY
  2 DESC
LIMIT
  300

问题中的旧版SQL等效项实际上也具有使数组变平的效果，尽管它隐含在主题的GROUP BY中。