每行的SUM和过滤结果SUM IN $ x

Question

我的表格在Postgres中的数据：

id  user_id sell_amount sell_currency_id    buy_amount  buy_currency_id type    status  date_add
5   2   2.00000000  1   4.00000000  0   0   0   2013-12-15 19:06:40
6   3   2.60000000  1   5.10000000  0   0   0   2013-12-15 19:06:54 
4   1   1.00000000  1   0.80000000  0   0   0   2013-12-15 19:07:05
7   4   4.00000000  1   8.20000000  0   0   0   2013-12-15 19:07:21
8   5   3.00000000  1   6.00000000  0   1   0   2013-12-15 19:07:40

我必须从此表中选择id，user_id，sell_amount，sell_currency_id status=0和type=0以及SUM }到当前行IN $ x，按ORDER BY buy_amount/sell_amount ASC排序，date_add ASC

$x = 6

的结果

id  user_id sell_amount sell_currency_id    SUM(sell_amount)
4   1   1.00000000  1   1.00000000
6   3   2.60000000  1   3.60000000
5   2   2.00000000  1   5.60000000
7   4   4.00000000  1   9.60000000

Answer 1

你需要累积金额，Postgres提供。这个逻辑有点棘手。您希望第一个值大于或等于$x。

select id, user_id, sell_amount, sell_currency
from (select id, user_id, sell_amount, sell_currency,
             sum(sell_amount) over (order by buy_amount/sell_amount ASC, date_add ASC) as cumsell
      from table t
      where status = 0 and type = 0
     ) t
where $x <= cumsell and $x > cumsell - sell_amount;