mysql - SQL 平衡计算按日期排序

Question

我有 2 个表 AmountIn 和 AmountOut。

第一个表 Amountin 看起来像:

数量

+--------+--------------+-----------+
| account| date         | AmountIn  |
+--------+--------------+-----------+
| A      |  2017/2/6    | 200       |
| A      |  2017/2/5    | 100       |
| A      |  2017/2/5    | 500       |
| B      |  2017/2/1    | 1000      |
| B      |  2017/2/1    | 2000      |
| C      |  2017/1/20   | 25        |
+--------+----+---------+-----------+

第二个看起来像:

出金额

+--------+--------------+-----------+
| account| date         |AmountOut  |
+--------+--------------+-----------+
| A      |  2017/2/8    | 200       |
| A      |  2017/2/7    | 100       |
| A      |  2017/2/6    | 500       |
| B      |  2017/2/2    | 1000      |
| B      |  2017/2/1    | 2000      |
| C      |  2017/1/20   | 25        |
+--------+----+---------+-----------+

现在我想要一个显示结果如下的查询:对于帐户 A

+--------+--------------+----------+-----------+------------+
| account| date         | AmountIn | AmountOut | Balancy    |
+--------+--------------+-------- -+-----------+------------+
| A      |  2017/2/8    | 0        | 200       | 0          |
| A      |  2017/2/7    | 0        | 100       | 200        |
| A      |  2017/2/6    | 200      | 0         | 300        |
| A      |  2017/2/6    | 0        | 500       | 100        |
| A      |  2017/2/5    | 100      | 0         | 600        |
| A      |  2017/2/5    | 500      | 0         | 500        |
+--------+----+---------+----------+-----------+------------+

这意味着合并两个表并计算 balancy 为:

last balance + AmountIn - AmounOut  

我的代码是:

select
    t.*,
    @sum := if(@account = account, 
                @sum + AmountIn - AmountOut,
                if((@account := account) is not null,
                    AmountIn - AmountOut, 0)
            ) balance
from (
    select
        *
    from (
        select
            1 x,
            account,
            date,
            AmountIn,
            0 AmountOut
        from AmountIn
        union all
        select
            0 x,
            account,
            date,
            0 AmountIn,
            AmountOut
        from AmountOut
    ) t order by account, date, x
) t cross join (select @account := null, @sum := 0) t2 

但它给我的结果是按日期升序排列的，我希望它按日期降序排列。我不需要在顶部看到最后的操作，否则当数据不足时，我将很难向下滚动或转到下一页请帮忙

Answer 1

这是一个通过 txn 建立平衡的解决方案。我使用 unionall(没有连接)来构建初始表，因为在您的示例中，您似乎不希望同时包含 amountin 和 amountout 的行:

select * 
from (
select 
@cnt := If(@prev=account , @cnt+1,1) rown, a.*,
@balance := if(  @prev=account, @balance + amountin - amountout, amountin - amountout) balance,                                                           
@prev := account prev  from 
(select account, date, amountin, 0 amountout from amountin
union all
select account, date, 0, amountout from amountout) a, (select @cnt := 1) b, (select @prev :='') c, (select @balance :=0) bal
order by account, date
    ) r
    order by account, rown desc, date desc

Here is a working exmaple with your data