谷歌BigQuery,我使用'免费'功能时丢失了空行

Question

#StandardSQL
WITH tableA AS (
SELECT ["T001", "T002", "T003"] AS T_id, [1, 5] AS L_id
UNION ALL
SELECT ["T008", "T009"] AS T_id, NULL AS L_id
)

SELECT * FROM tableA, UNNEST(L_id) AS unnest

当我执行此代码时,我期望结果如下.

RowNumber  T-id            L-id  unnest
1          T001,T002,T003  1,5   1
2          T001,T002,T003  1,5   5
3          T004,T005       NULL  NULL

但我得到了结果......

RowNumber  T-id            L-id  unnest
1          T001,T002,T003  1,5   1
2          T001,T002,T003  1,5   5

我输掉了第三排.然后,我看到了谷歌的官方文档.有这样写的.

UNNEST treats NULL as follows.
 ?NULL and empty ARRAY generate zero rows.
 ?An ARRAY containing NULL generates a row containing a NULL value.

但我不想丢失我的空行.

我怎么能保持空行？

请告诉我解决方案......

Answer 1

而不是CROSS JOIN,使用LEFT JOIN.这将为空数组返回一个带空值的行.您可能还对文档中使用数组主题感兴趣.

#StandardSQL
WITH tableA AS (
  SELECT ["T001", "T002", "T003"] AS T_id, [1, 5] AS L_id
  UNION ALL
  SELECT ["T008", "T009"] AS T_id, NULL AS L_id
)
SELECT * FROM tableA
LEFT JOIN UNNEST(L_id) AS value;