Sql 清点后如何计算平均值？

清点后我想取平均数

以下是我当前的查询：

SELECT product_id,
         COUNT(DISTINCT shop_id) AS shops,
         year,
         month,
         day
FROM X
GROUP BY  product_id, year, month, day

但是现在，我想取商店的平均值。我尝试过类似的方法，但我得到了一个错误：invalidrequestexception

SELECT product_id,
         AVG(COUNT(DISTINCT shop_id) AS shops) as avg_shops,
         year,
         month,
         day
FROM X
GROUP BY  product_id, year, month, day

试试下面这样

with cte as
(
SELECT product_id,
         COUNT(DISTINCT shop_id) AS shops,
         year,
         month,
         day
FROM X
GROUP BY  product_id, year, month, day
) select product_id,
         AVG(shops) AS  as avg_shops,
         year,
         month,
         day
FROM cte
GROUP BY  product_id, year, month, day 

试试下面这样

with cte as
(
SELECT product_id,
         COUNT(DISTINCT shop_id) AS shops,
         year,
         month,
         day
FROM X
GROUP BY  product_id, year, month, day
) select product_id,
         AVG(shops) AS  as avg_shops,
         year,
         month,
         day
FROM cte
GROUP BY  product_id, year, month, day 

---

如果只需要平均值，请使用子查询：

SELECT AVG(shops)
FROM (SELECT product_id, COUNT(DISTINCT shop_id) AS shops
      FROM X
      GROUP BY product_id, year, month, day
     ) x

---

如果只需要平均值，请使用子查询：

SELECT AVG(shops)
FROM (SELECT product_id, COUNT(DISTINCT shop_id) AS shops
      FROM X
      GROUP BY product_id, year, month, day
     ) x

---

样本数据和期望的结果会有帮助。样本数据和期望的结果会有帮助。我应该删除查询末尾的X吗？@zineda。它是一个表别名。没有必要删除它。@GordonLinoff-我认为如果你把或作为制表符，它会更清晰-尽管Oracle出于某种原因完全无法理解这种语法@维拉斯。我从不将as用于表别名，只用于列别名。@zineda-如果删除它，查询将无法工作。查询的第一部分也可以写为SELECT AVGx.shops FROM SELECT…-看看我的小提琴。尝试删除它并查看-SQL Server的错误消息信息不是很丰富，但例如PostgreSQL和MySQL，它会告诉您该错误：FROM中的子查询必须有别名-请自己尝试并查看！我应该删除查询末尾的X吗？@zineda。它是一个表别名。没有必要删除它。@GordonLinoff-我认为如果你把或作为制表符，它会更清晰-尽管Oracle出于某种原因完全无法理解这种语法@维拉斯。我从不将as用于表别名，只用于列别名。@zineda-如果删除它，查询将无法工作。查询的第一部分也可以写为SELECT AVGx.shops FROM SELECT…-看看我的小提琴。尝试删除它并查看-SQL Server的错误消息信息不是很丰富，但例如PostgreSQL和MySQL，它会告诉您该错误：FROM中的子查询必须有别名-请自己尝试并查看！