如何用UNNEST或任何其他函数展平数组？

Question

假设我得到一个临时表,其中一个字段是一个数组,如何将其转换为多行？

使用PostgreSQL,可以使用UNNEST http://sqlfiddle.com/#!15/21673/19完成

WITH x AS (SELECT ARRAY[1,3,2] AS arr)

SELECT UNNEST(arr) FROM x

在BigQuery中运行相同的查询说法语错误:[3:8]处的意外关键字UNNEST

似乎在BigQuery中,UNNEST只能在FROM子句之后放入,

然后我试过这些:

WITH x AS (SELECT ARRAY[1,3,2] AS arr)

SELECT * FROM UNNEST(x)

这个说UNNEST不能用在桌子上:x在[3:22] ; 或这个

WITH x AS (SELECT ARRAY[1,3,2] AS row)

SELECT * FROM UNNEST(x.arr)

说UNNEST不适用于桌子:x.arr at [3:22]

BTW,当前的临时表x如下所示:

WITH x AS (SELECT ARRAY[1,2] AS row)

SELECT * FROM x
EOF

+--------------+
|     row      |
+--------------+
| [u'1', u'2'] |
+--------------+

而我期待把它变成有价值的行:

+-----+
| row |
+-----+
|   1 |
|   2 |
+-----+

Answer 1

还有另一个版本 - 涉及"明确的"UNNEST

WITH x AS (SELECT ARRAY[1,3,2] AS arr)
SELECT arr_item FROM x, UNNEST(arr) as arr_item

Answer 2

你可以通过对x的每一行执行arr元素的CROSS JOIN来进行这样的展平,即

WITH x AS (SELECT ARRAY[1,3,2] AS arr)
SELECT arr FROM x, x.arr

或者您可以更明确地将其写为CROSS JOIN而不是使用逗号

WITH x AS (SELECT ARRAY[1,3,2] AS arr)
SELECT arr FROM x CROSS JOIN x.arr