Sql 每行总和和筛选结果总和，单位为$x

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

我必须从该表中选择id、用户id、销售金额、销售货币id，状态为0，类型为0，并以$x的形式汇总到当前行，按订单按购买金额/销售金额ASC、日期添加ASC

$x=6的结果

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你需要一个累计金额，这是Postgres提供的。这样的逻辑就有点复杂了。您需要大于或等于$x的第一个值

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

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;