Bigquery：STRUCT (*) 语法

Question

如何在不指定名称的情况下自动将 STRUCT 应用到 table 中的所有字段？

无效示例：

WITH data as (
 SELECT 'Alex' as name, 14 as age, 'something else 1' other_field
UNION ALL 
 SELECT 'Bert' as name, 14 as age, 'something else 2' other_field
UNION ALL 
 SELECT 'Chiara' as name, 13 as age, 'something else 3' other_field
)

SELECT AS STRUCT(SELECT * except (other_field) from data) as student_data

Returns: Error: Scalar subquery cannot have more than one column unless using SELECT AS STRUCT to build STRUCT values at [9:17]

然而这有效：

WITH data as (
 SELECT 'Alex' as name, 14 as age, 'something else 1' other_field
UNION ALL 
 SELECT 'Bert' as name, 14 as age, 'something else 2' other_field
UNION ALL 
 SELECT 'Chiara' as name, 13 as age, 'something else 3' other_field
)

SELECT STRUCT(name,age) as student_data

from data

问题是，一旦我有 100 列，其中只有 5 列不属于，把它们写出来会让我发疯。有没有更简单的方法来使用某些版本的 Select * Except()?

Answer 1

下面是 BigQuery 标准 SQL

#standardSQL
WITH data AS (
  SELECT 'Alex' AS name, 14 AS age, 'something else 1' other_field UNION ALL 
  SELECT 'Bert' AS name, 14 AS age, 'something else 2' other_field UNION ALL 
  SELECT 'Chiara' AS name, 13 AS age, 'something else 3' other_field
)
SELECT (
  SELECT AS STRUCT * EXCEPT(other_field)
  FROM UNNEST([t])
  ) AS student_data
FROM data t

输出

Row student_data.name   student_data.age     
1   Alex                14   
2   Bert                14   
3   Chiara              13

Answer 2

您需要 AS STRUCT expr

的表达式

SELECT AS STRUCT data.* except (other_field) from data

Answer 3

作为对 Mikhail Berlyant 回答的更新因为评论部分不允许我使用正确的格式：

请注意，您可能需要将 SELECT AS STRUCT * EXCEPT(other_field) 括在 () 中。 UNNEST([t]) 部分不是必需的。 IE。这也有效：

#standardSQL
WITH data AS (
  SELECT 'Alex' AS name, 14 AS age, 'something else 1' other_field UNION ALL 
  SELECT 'Bert' AS name, 14 AS age, 'something else 2' other_field UNION ALL 
  SELECT 'Chiara' AS name, 13 AS age, 'something else 3' other_field
)
SELECT
  (SELECT AS STRUCT data.* EXCEPT(other_field)) as student_data,
FROM data

Bigquery：STRUCT (*) 语法

Bigquery: STRUCT (*) syntax

struct

google-bigquery

except