如何在 BigQuery 中声明列表/数组/结构类型变量

Question

如何在 BigQuery 中声明列表类型变量，以便我可以在 where 子句中使用它？我有这个代码

WITH
  subquery AS (
  SELECT
    1 AS col1
  UNION ALL
  SELECT
    2 AS col1
  UNION ALL
  SELECT
    3 AS col1 )

SELECT
  col1
FROM
  subquery
WHERE
  col1 IN (1, 2)

相反，我想在查询中使用变量

DECLARE list ARRAY;
SET list = (1,2);

WITH
  subquery AS (
  SELECT
    1 AS col1
  UNION ALL
  SELECT
    2 AS col1
  UNION ALL
  SELECT
    3 AS col1 )

SELECT
  col1
FROM
  subquery
WHERE
  col1 IN list

我试过 DECLARE list STRUCT [less than] int64,int64 [greater than] 它不接受

Answer 1

试试下面的代码：

DECLARE list ARRAY <INT64>;
SET list = [1,2];

WITH
  subquery AS (
  SELECT
    1 AS col1
  UNION ALL
  SELECT
    2 AS col1
  UNION ALL
  SELECT
    3 AS col1 )

SELECT
  col1
FROM
  subquery
WHERE
  col1 IN UNNEST(list)

Answer 2

您可以DECLARE一次性为数组分配值，而无需使用SET. 例子：

DECLARE myArray ARRAY <STRING> DEFAULT ["FIRST", "SECOND", "THIRD"];

SELECT myValues
  FROM UNNEST(myArray) AS myValues

您可能更喜欢使用子查询WITH。例子：

WITH myArray AS (
  SELECT *
    FROM UNNEST(["FIRST", "SECOND", "THIRD"]) AS myValues
)
SELECT myValues
  FROM myArray

两个查询将提供相同的结果：

+----------+
| myValues |
+----------+
| FIRST    |
| SECOND   | 
| THIRD    |
+----------+