Postgres 聚合條件總和

Question

我正在嘗試對訂單總重量的條件產品求和（我希望這是有道理的）。 我得到錯誤：

錯誤：聚合函數調用不能嵌套
第 6 行：, SUM ( CASE WHEN pc.type = 'TEES' THEN (SUM (opd.qt ...

這是查詢摘錄：

SELECT DISTINCT
         o.work_order_number dn
       , SUM(opd.qty) units
       , SUM (CASE  WHEN pc.type = 'TEES' THEN (SUM (opd.qty) * .75)
            WHEN pc.type = 'JERSEYS' THEN (SUM (opd.qty) * 1.5)
        END) AS weight

Answer 1

嘗試：

SELECT o.work_order_number dn 
     , SUM(opd.qty) units 
     , SUM ( opd.qty * CASE pc.type 
                           WHEN 'TEES' THEN 0.75 
                           WHEN 'JERSEYS' THEN 1.5 
                       END ) AS weight
FROM ...
GROUP BY o.work_order_number

Answer 2

那么你可以做的是嵌套你的選擇語句 例如

select sum(weight),sum(etc) 
from (
    SELECT DISTINCT o.work_order_number dn 
                 , (opd.qty) units 
                 , ( CASE WHEN pc.type = 'TEES' THEN ((opd.qty) * .75) 
                          WHEN pc.type = 'JERSEYS' THEN ((opd.qty) * 1.5) END) AS weight)
).

所以第一個 select 語句處理你的 case 語句，第二個 select 語句總結你的字段。