的Oracle SQL NTILE - 平等分配

Question

這個查詢：

SELECT min("x") as "From", 
     max("x") as "To", 
     sum("quantity") 
FROM (
SELECT t.*, 
     ntile(4) over (order by "x") as group_no 
FROM table1 t)GROUP BY 
       group_no 
       ORDER BY 1; 

與此數據

x quantity 
1 9 
2 43 
3 21 
4 26 
6 14 
7 38 
8 14 
9 20 
10 20 
11 30 
12 32 
13 37 
14 27 
15 22 
16 34 
17 9 
18 4 
19 24 
20 42 
21 21 
22 16 
23 34 
24 9 
25 49 
26 21 
27 20 
28 28 
29 6 
30 3 

有這樣的結果：

1 6 113 
7 11 122 
12 16 152 
17 21 100 
22 26 129 
27 30 57 

是否有任何其他SQL可能性總和（數量）更平均分配？ 。

我知道有很多的算法，但我敢肯定，必須有智能SQL（解析函數）解決方案，如

Answer 1

嘗試是這樣的：

 

    select 
     min(b.x) as "From", 
     max(b.x) as "To", 
     sum(b.quantity) as "Sum" 
    from 
     (
     select 
      a.x, 
      a.quantity, 
      ceil(sum(a.quantity) 
      over (order by a.x asc rows between unbounded preceding and current row)/a.avg_quantity_for_group) group_no 
     from (select t.x, t.quantity, ceil(sum(t.quantity) over()/4) avg_quantity_for_group from table1 t) a 
    ) b 
    group by b.group_no 
    order by "From" asc; 

對於輸入數據結果將是：

 
1 8 165 
9 14 166 
15 22 172 
23 30 170