BigQuery：使用 SQL 从辅助表中查找 ID 数组并连接数据

Question

我有一个如下的数据结构：

产品

| _id |  name  | available_in_region_id |
-----------------------------------------
| d22 |  shoe  | c32, a43, x53          |
| t64 |  hat   | c32, f42               |

地区

| _id |  name       |
---------------------
| c32 |  london     |
| a43 |  manchester |
| x53 |  bristol    |
| f42 |  liverpool  |

我想查找“available_in_region_id” id 的数组并将它们替换为区域名称，以生成如下表：

| _id |  name  | available_in_region_name    |
----------------------------------------------
| d22 |  shoe  | london, manchester, bristol |
| t64 |  hat   | london, liverpool           |

使用标准 SQL 执行此操作的最佳方法是什么？

谢谢，

一个

Answer 1

以下是 BigQuery 标准 SQL

#standardSQL
SELECT p._id, p.name, 
  STRING_AGG(r.name, ', ' ORDER BY OFFSET) AS available_in_region_name
FROM `project.dataset.Products` p,
UNNEST(SPLIT(available_in_region_id, ', ')) rid WITH OFFSET
LEFT JOIN `project.dataset.Regions` r
ON rid = r._id
GROUP BY _id, name

您可以使用您问题中的示例数据进行测试，如以下示例所示

#standardSQL
WITH `project.dataset.Products` AS (
  SELECT 'd22' _id, 'shoe' name, 'c32, a43, x53' available_in_region_id UNION ALL
  SELECT 't64', 'hat', 'c32, f42'
), `project.dataset.Regions` AS (
  SELECT 'c32' _id, 'london' name UNION ALL
  SELECT 'a43', 'manchester' UNION ALL
  SELECT 'x53', 'bristol' UNION ALL
  SELECT 'f42', 'liverpool' 
)
SELECT p._id, p.name, 
  STRING_AGG(r.name, ', ' ORDER BY OFFSET) AS available_in_region_name
FROM `project.dataset.Products` p,
UNNEST(SPLIT(available_in_region_id, ', ')) rid WITH OFFSET
LEFT JOIN `project.dataset.Regions` r
ON rid = r._id
GROUP BY _id, name  

有输出

Row _id name    available_in_region_name     
1   d22 shoe    london, manchester, bristol  
2   t64 hat     london, liverpool