基於整列的平均值過濾表格

Question

我試圖根據列的平均值過濾表格，但不知何故它不起作用。它不會返回任何東西。平均值大約爲102，用它替代AVG子句會返回正確的行。

我怎樣才能讓它正常工作？

SELECT 
ce.customer_id, 
ce.first_name, 
ce.total 

FROM 
(SELECT 
p.customer_id, 
c.first_name, 
SUM(p.amount) AS total 

FROM payment as p 
JOIN customer as c ON p.customer_id=c.customer_id 
GROUP BY p.customer_id,c.first_name) AS ce 

GROUP BY ce.customer_id,ce.first_name,ce.total 

HAVING ce.total > AVG(ce.total) 

Answer 1

您的查詢有多個錯誤。外部GROUP BY沒有意義。

我的建議是使用窗口函數。在這種情況下，你想要的總的平均水平，所以這看起來像：

SELECT ce.customer_id, ce.first_name, ce.total 
FROM (SELECT p.customer_id, c.first_name, SUM(p.amount) AS total, 
      AVG(SUM(p.amount)) OVER() as avg_total 
     FROM payment p JOIN 
      customer c 
      ON p.customer_id = c.customer_id 
     GROUP BY p.customer_id, c.first_name 
    ) ce 
WHERE ce.total > avg_total