如何将 AVG 计算为 2 个表之间的左连接？

Question

我必须计算 bigquery 的平均总收入（关键是 item_id）。

SELECT
  t0.order_create_date AS day,
  t0.site_country AS country,
  p0.product_brand AS brand,
  p0.product_gender AS gender,
  p0.product_department AS department,
  t0.item_qty AS items_sold,
  t0.item_sale_price AS gross_revenue,
  t0.item_net_price AS net_revenue,
FROM
  `transactions` t0
LEFT JOIN
  `products` p0
ON
  t0.item_id = p0.item_id
ORDER BY
  country,
  day ASC

我试过这个：

SELECT
  t0.order_create_date AS day,
  t0.site_country AS country,
  p0.product_brand AS brand,
  p0.product_gender AS gender,
  p0.product_department AS department,
  t0.item_qty AS items_sold,
  t0.item_sale_price AS gross_revenue,
  AVG(t0.item_sale_price) AS average_value,

  t0.item_net_price AS net_revenue,
FROM
  `transactions` t0
LEFT JOIN
  `products` p0
ON
  t0.item_id = p0.item_id
ORDER BY
  country,
  day ASC

双查询结果：

SELECT list expression references t0.order_create_date which is neither grouped nor aggregated at [2:3]

Answer 1

问题是您没有聚合或按所有其他列进行聚合，除了average_value之一。 在这里，您可以阅读有关 Group By 的更多信息。

从您正在创建的列的名称中，我想您还希望获得其他信息，例如总收入和净收入。 您也必须在它们上使用一些聚合 function ，否则错误将继续。

像下面这样的东西应该可以工作：

SELECT
  t0.order_create_date AS day,
  t0.site_country AS country,
  p0.product_brand AS brand,
  p0.product_gender AS gender,
  p0.product_department AS department,
  sum(t0.item_qty) AS items_sold,
  sum(t0.item_sale_price) AS gross_revenue,
  AVG(t0.item_sale_price) AS average_value,
  sum(t0.item_net_price) AS net_revenue,

FROM
  transactions t0
LEFT JOIN
  products p0
ON
  t0.item_id = p0.item_id

GROUP BY
  day,
  country,
  brand,
  gender,
  department

ORDER BY
  country,
  day ASC