Question

我有一列名为submission_date的列，其中包含json单元格，如下所示：

{"submitted":["January 24, 2019","January 25, 2019","January 30,
2019","February 27, 2019"],"submission_canceled":["January 24, 
2019","January 25, 2019"],"returned":"February 19, 2019"}

或类似这样：

{"submitted":["February 27, 2019","March 5, 2019"],"submission_canceled":"March 5, 2019"}

我可以轻松地从“ submission_canceled”字段中获得第一个结果：

json_extract(submission_date, "$.submission_canceled[0]")

我想如果我想保持价值，我会这么做：

json_extract(submission_date, "$.submission_canceled[-1]")

但这只是给我一个空值。如您所见，有时submission_canceled字段在列表中将有多个日期，而在其他时候，它将仅具有单个日期而不是在列表中。我想从submission_canceled部分获取列表中的单个项目或最后一个项目。

Answer 1

以下示例适用于BigQuery标准SQL

#standardSQL
WITH `project.dataset.table` AS (
  SELECT 1 id, '{"submitted":["January 24, 2019","January 25, 2019","January 30, 2019","February 27, 2019"],"submission_canceled":["January 24,  2019","January 25, 2019"],"returned":"February 19, 2019"}' submission_date UNION ALL
  SELECT 2, '{"submitted":["February 27, 2019","March 5, 2019"],"submission_canceled":"March 5, 2019"}'
)
SELECT id, REGEXP_REPLACE(ARRAY_REVERSE(SPLIT(JSON_EXTRACT(submission_date, '$.submission_canceled'), '","'))[OFFSET(0)], r'"|\[|\]', '') last_submission_canceled
FROM `project.dataset.table`

有结果

Row id  last_submission_canceled     
1   1   January 25, 2019     
2   2   March 5, 2019

更新-以下是“较轻”版本

#standardSQL
WITH `project.dataset.table` AS (
  SELECT 1 id, '{"submitted":["January 24, 2019","January 25, 2019","January 30, 2019","February 27, 2019"],"submission_canceled":["January 24,  2019","January 25, 2019"],"returned":"February 19, 2019"}' submission_date UNION ALL
  SELECT 2, '{"submitted":["February 27, 2019","March 5, 2019"],"submission_canceled":"March 5, 2019"}'
)
SELECT id, REGEXP_EXTRACT(JSON_EXTRACT(submission_date, '$.submission_canceled'), r'"([^"]*)"\]?$') last_submission_canceled
FROM `project.dataset.table`

具有明显相同的结果

Row id  last_submission_canceled     
1   1   January 25, 2019     
2   2   March 5, 2019

从Cell中的JSON中提取最后一项

1 个答案: