SQL/Presto 将列表列扩展为多行
SQL/Presto expanding a list column into multiple rows
给了一个蜂巢table喜欢
a | b
----------
1 | [1,2,3]
2 | [2,3]
如何创建辅助 table 喜欢
a | b
------
1 | 1
1 | 2
1 | 3
2 | 2
2 | 3
这是unnest的教科书案例：
-- sample data
WITH dataset (a, b) AS (
VALUES (1, array[1,2,3]),
(2, array[2,3])
)
-- query
select a, bb
from dataset
cross join unnest(b) as t(bb)
order by a, bb -- to pretify output
输出：
a
bb
1
1
1
2
1
3
2
2
2
3
给了一个蜂巢table喜欢
a | b
----------
1 | [1,2,3]
2 | [2,3]
如何创建辅助 table 喜欢
a | b
------
1 | 1
1 | 2
1 | 3
2 | 2
2 | 3
这是unnest的教科书案例：
-- sample data
WITH dataset (a, b) AS (
VALUES (1, array[1,2,3]),
(2, array[2,3])
)
-- query
select a, bb
from dataset
cross join unnest(b) as t(bb)
order by a, bb -- to pretify output
输出：
| a | bb |
|---|---|
| 1 | 1 |
| 1 | 2 |
| 1 | 3 |
| 2 | 2 |
| 2 | 3 |