过滤数组
以下示例在 ARRAY() 运算符的子查询中使用 WHERE 子句,以过滤返回的行。
WITH sequences AS
(SELECT [0, 1, 1, 2, 3, 5] AS some_numbers
UNION ALL SELECT [2, 4, 8, 16, 32] AS some_numbers
UNION ALL SELECT [5, 10] AS some_numbers)
SELECT
ARRAY(SELECT x * 2
FROM UNNEST(some_numbers) AS x
WHERE x < 5) AS doubled_less_than_five
FROM sequences;
+------------------------+
| doubled_less_than_five |
+------------------------+
| [0, 2, 2, 4, 6] |
| [4, 8] |
| [] |
+------------------------+
WITH sequences AS
(SELECT [0, 1, 1, 2, 3, 5] AS some_numbers)
SELECT ARRAY(SELECT DISTINCT x
FROM UNNEST(some_numbers) AS x) AS unique_numbers
FROM sequences;
+-----------------+
| unique_numbers |
+-----------------+
| [0, 1, 2, 3, 5] |
+-----------------+
WITH sequences AS
(SELECT [0, 1, 1, 2, 3, 5] AS some_numbers
UNION ALL SELECT [2, 4, 8, 16, 32] AS some_numbers
UNION ALL SELECT [5, 10] AS some_numbers)
SELECT
ARRAY(SELECT x
FROM UNNEST(some_numbers) AS x
WHERE 2 IN UNNEST(some_numbers)) AS contains_two
FROM sequences;
+--------------------+
| contains_two |
+--------------------+
| [0, 1, 1, 2, 3, 5] |
| [2, 4, 8, 16, 32] |
| [] |
+--------------------+