根据 BigQuery 中嵌套字段的不同值选择行

Question

我在 BigQuery 中有一个如下所示的表：

sequence 字段是重复的RECORD。我想每个stepName 选择一行，但是如果每个步骤名称有多行，我想选择sequence.step.elapsedSeconds 和sequence.step.elapsedMinutes 不为空的行，否则选择其中的行这些列是空的。

如上图所示，我想选择行号。 2、4 和 5。我计算出 ROW_NUMBER 是这样的：ROW_NUMBER() OVER(PARTITION BY step.stepName) AS RowNum。

这是我目前尝试过滤掉不需要的行的查询：

WITH DistinctRows AS
(
select timestamp, 
  ARRAY (
    SELECT 
      STRUCT(
        STRUCT(
          step.elapsedSeconds, 
          step.elapsedMinutes, 
        ) as step
      ) 
    FROM 
      UNNEST(source_table.sequence) AS sequence
  ) AS sequence, 
  ROW_NUMBER() OVER(PARTITION BY step.stepName) AS RowNum
from source_table,
unnest(sequence) as previousCalls
order by timestamp asc
)

    SELECT *
    FROM DistinctRows,
    unnest(sequence) as sequence
    where (rowNum = 1 and (step.elapsedSeconds is null and step.elapsedMinutes is null)
    or (RowNum > 1 and step.elapsedSeconds is not null and step.elapsedSeconds is not null)
    order by timestamp asc

我需要帮助来弄清楚如何过滤掉像 no 这样的行。 1 和 3，希望能得到一些帮助。

提前致谢。

Answer 1

嗯。 . .假设stepname 不是重复列的一部分：

SELECT dr.* EXCEPT (sequence),
       (SELECT seq
        FROM unnest(dr.sequence) seq
        ORDER BY seq.step.elapsedSeconds DESC NULLS LAST, 
                 sequence.step.elapsedMinutes DESC NULLS LAST
       ) as sequence
FROM DistinctRows dr
ORDER BY timestamp asc;

如果stepname 是sequence 的一部分，则子查询将重新聚合：

SELECT dr.* EXCEPT (sequence),
       (SELECT ARRAY_AGG(sequence ORDER BY stepName)
        FROM (SELECT seq,
                     ROW_NUMBER() OVER (PARTITION BY seq.stepName
                                        ORDER BY seq.step.elapsedSeconds DESC NULLS LAST,  sequence.step.elapsedMinutes DESC NULLS
                                       ) as seqnum
              FROM unnest(dr.sequence) seq
             ) s
        WHERE seqnum = 1
       ) as sequence
FROM DistinctRows dr
ORDER BY timestamp asc