从 Bigquery 中的行创建新列

Question

我有一个如下所示的表格，其中显示了产品的购物车

每个id有不同的产品，例如：id 1有3个产品，id 2有4个...但每个id的最大产品是10个。时间戳按DESC排序。所以现在我想像这样转换这个表：

表的架构：

我在这里尝试了在 BigQuery 中透视重复字段的解决方案，但列数太多。如何让新列最多对应 10 个产品

谢谢

Answer 1

以下选项适用于 BigQuery 标准 SQL

#standardSQL
SELECT id, 
  products[SAFE_OFFSET(0)].product_id product_id_1,
  products[SAFE_OFFSET(0)].price price_1,
  products[SAFE_OFFSET(1)].product_id product_id_2,
  products[SAFE_OFFSET(1)].price price_2,
  products[SAFE_OFFSET(2)].product_id product_id_3,
  products[SAFE_OFFSET(2)].price price_3,
  products[SAFE_OFFSET(3)].product_id product_id_4,
  products[SAFE_OFFSET(3)].price price_4,
  products[SAFE_OFFSET(4)].product_id product_id_5,
  products[SAFE_OFFSET(4)].price price_5,
  products[SAFE_OFFSET(5)].product_id product_id_6,
  products[SAFE_OFFSET(5)].price price_6,
  products[SAFE_OFFSET(6)].product_id product_id_7,
  products[SAFE_OFFSET(6)].price price_7,
  products[SAFE_OFFSET(7)].product_id product_id_8,
  products[SAFE_OFFSET(7)].price price_8,
  products[SAFE_OFFSET(8)].product_id product_id_9,
  products[SAFE_OFFSET(8)].price price_9,
  products[SAFE_OFFSET(9)].product_id product_id_10,
  products[SAFE_OFFSET(9)].price price_10
FROM `project.dataset.table`

或者

#standardSQL
SELECT id, 
  MAX(IF(off = 0, product_id, NULL)) product_id_1,
  MAX(IF(off = 0, price, NULL)) price_1,
  MAX(IF(off = 1, product_id, NULL)) product_id_2,
  MAX(IF(off = 1, price, NULL)) price_2,
  MAX(IF(off = 2, product_id, NULL)) product_id_3,
  MAX(IF(off = 2, price, NULL)) price_3,
  MAX(IF(off = 3, product_id, NULL)) product_id_4,
  MAX(IF(off = 3, price, NULL)) price_4,
  MAX(IF(off = 4, product_id, NULL)) product_id_5,
  MAX(IF(off = 4, price, NULL)) price_5,
  MAX(IF(off = 5, product_id, NULL)) product_id_6,
  MAX(IF(off = 5, price, NULL)) price_6,
  MAX(IF(off = 6, product_id, NULL)) product_id_7,
  MAX(IF(off = 6, price, NULL)) price_7,
  MAX(IF(off = 7, product_id, NULL)) product_id_8,
  MAX(IF(off = 7, price, NULL)) price_8,
  MAX(IF(off = 8, product_id, NULL)) product_id_9,
  MAX(IF(off = 8, price, NULL)) price_9,
  MAX(IF(off = 9, product_id, NULL)) product_id_10,
  MAX(IF(off = 9, price, NULL)) price_10
FROM `project.dataset.table`,
UNNEST(products) product WITH OFFSET off
GROUP BY id