google-bigquery - 如何在 BigQuery 中为一组加星标的列设置别名？

Question

考虑：

• users带列的表id，
• 表features, 列id, day, x, y, 和z.

我的查询是：

SELECT
  users.*,
  a.* EXCEPT(id, day),
  b.* EXCEPT(id, day)
FROM
  users
  LEFT JOIN features AS a
    ON users.id = a.id
    AND a.day = DATE("2021-04-14")
  LEFT JOIN features AS b
    ON users.id = b.id
    AND b.day = DATE("2020-01-01")

它返回以下列：

id | x | y | z | x_1 | y_2 | z_3
--------------------------------
...

有没有办法用自定义后缀给列起别名？就像是：

SELECT
  a.* AS *_from_a,
  b.* AS *_from_b

要获得：

id | x_from_a | y_from_a | z_from_a | x_from_b | y_from_b | z_from_b
--------------------------------------------------------------------
...

标签： google-bigquery

Answer 1

以下是我能想到的选项（不完全是您期望的方式 - 但我认为会达到您的目标）

SELECT
  a as from_a,
  b as from_b
FROM
  mytable AS a,
  mytable AS b    

将在下方返回