SELECT SUM as field

Question

假設我有這張表

表（a，b，c，d）。數據類型不重要。

我想這樣做

select a as a1,b as b1,c as c1, 
     (select sum(d) from table where a=a1 and b=b1) as total 
from table 
group by a,b,c 

...但我不能找到一種方法（「FROM子句中未找到」的SQLDeveloper保持與抱怨。）

有沒有辦法？可能嗎？

Answer 1

SELECT a as a1,b as b1,c as c1, 
     (
     SELECT SUM(d) 
     FROM mytable mi 
     WHERE mi.a = mo.a 
       AND mi.b= mo.b 
     ) as total 
FROM mytable 
GROUP BY 
     a, b, c 

它更簡單，高效重寫它作爲這樣的：

SELECT a AS a1, B AS b1, c AS c1, SUM(SUM(d)) OVER (PARTITION BY a, b) AS total 
FROM mytable 
GROUP BY 
     a, b, 

注意SUM(SUM(d))這裏。

最內層的SUM是聚合函數。它會計算SUM(d)a-b-c -wise。

最外層的SUM是分析函數。它將預先計算的SUM(d)的a-b相加，然後返回每一行的值。

Answer 2

杜你的意思是這樣的？

select a as a1, 
     b as b1, 
     c as c1, 
     sum(sum(d)) OVER (PARTITION BY a, b) AS total 
from table 
group by a,b,c 

Answer 3

你可以用別名做到這一點：

SELECT a AS a1, b AS b1, c AS c1, 
     (SELECT SUM(d) 
      FROM test_t t_in 
      WHERE t_in.a = t.a 
      AND t_in.b = t.b) AS total 
    FROM test_t t 
GROUP BY a, b, c