我的查询有一个NOT IN，突然停止显示结果

Question

我有一个每天运行的查询，突然它停止输出结果。它不会输出错误，只会输出结果。

请注意，此查询包含一个NOT IN运算符。

Answer 1

这是NOT IN行为的已知问题，请查看它的MySQL版本：

• MySQL "Not IN" query suddenly stopped returning results

使用BigQuery：

WITH data AS (
  SELECT * FROM UNNEST([1,2,3]) x
), data2 AS (
  SELECT * FROM UNNEST([1,2]) x
)

SELECT * FROM data
WHERE x NOT IN (SELECT * FROM data2)

3

但是如果data2中为空，则

WITH data AS (
  SELECT * FROM UNNEST([1,2,3]) x
), data2 AS (
  SELECT * FROM UNNEST([1,2,null]) x
)

SELECT * FROM data
WHERE x NOT IN (SELECT * FROM data2)

# no results

相反，您可以执行LEFT JOIN或NOT EXISTS：

WITH data AS (
  SELECT * FROM UNNEST([1,2,3]) x
), data2 AS (
  SELECT * FROM UNNEST([1,2]) x
)

SELECT * FROM data a
WHERE NOT EXISTS (SELECT * FROM data2 b WHERE a.x=b.x)

3