google-bigquery - 将 BigQuery javascript UDF 应用于组

Question

我正在尝试将 javascript 用户定义函数应用于组。在下面的代码中， -- group by my_groupinsidetuple被注释掉了。我想在每个 inside 上应用temptest函数。如果 group by 被注释掉，代码就会运行。如果我尝试包含 group by，它会产生一个“标量子查询产生了多个元素”。我应该进行哪些更改，以便我可以为每组输出一个数组 ( )？my_grouptest_datamy_group

#standardSQL create function
CREATE TEMP FUNCTION test(a ARRAY<STRING>) 
RETURNS ARRAY< STRING >
LANGUAGE js AS '''
  var combine = function(a) {
    var fn = function(n, src, got, all) {
      if (n == 0) {
        if (got.length > 0) {
          all[all.length] = got;
        } return;
      }
      for (var j = 0; j < src.length; j++) {
        fn(n - 1, src.slice(j + 1), got.concat([src[j]]), all);
      } return;
    }
    var all = [];
    for (var i = 1; i < a.length; i++) {
      fn(i, a, [], all);
    }
    all.push(a);
    return all;
  } 
  return combine(a)
''';

 WITH test_data AS (
  SELECT  'Shirt' item, 'Cashless' my_group UNION ALL
  SELECT  'Jeans', 'Cashless' UNION ALL
  SELECT  'Jeans', 'Cash' UNION ALL
  SELECT  'Cap', 'Cash' UNION ALL
  SELECT  'Shirt', 'Cash' UNION ALL
  SELECT  'Cap', 'Cashless'

),

tuple as (  
  SELECT ARRAY_AGG(DISTINCT item) items
  FROM test_data

  --group by my_group (uncommenting it creates error)
)

select * from unnest(test((select items from tuple)))

我正在寻找如下输出：

my_group    Item
Cash        Shirt
Cash        Jeans
Cash        Cap
Cash        Shirt,Jeans
Cash        Shirt,Cap
Cash        Jeans,Cap
Cash        Shirt,Jeans,Cap
Cashless    Shirt
Cashless    Jeans
Cashless    Cap
Cashless    Shirt,Jeans
Cashless    Shirt,Cap
Cashless    Jeans,Cap
Cashless    Shirt,Jeans,Cap

Answer 1

考虑下面（省略功能部分以保持答案足够紧凑......）

 WITH test_data AS (
  SELECT  'Shirt' item, 'Cashless' my_group UNION ALL
  SELECT  'Jeans', 'Cashless' UNION ALL
  SELECT  'Jeans', 'Cash' UNION ALL
  SELECT  'Cap', 'Cash' UNION ALL
  SELECT  'Shirt', 'Cash' UNION ALL
  SELECT  'Cap', 'Cashless'
), tuple as (  
  SELECT my_group, ARRAY_AGG(DISTINCT item) items
  FROM test_data
  group by my_group 
)
select my_group, item
from tuple,
unnest(test(items)) item    

带输出