如何从两个表中选择数据并将借方和贷方列中的余额相加（php）

Question

我有两张桌子

信用表

id     date      credit
1    4-1-2019     300
2   10-1-2019     500
3   10-2-2019     300

借记表

id     date      debit
1    2-1-2019     400
2   6-1-2019     600
3   2-2-2019     300

我想要一个表格来合并这些数据并显示余额，按日期排序

类似的东西

id     date      debit  credit  balance
1    2-1-2019     400            400
1    4-1-2019             300    100
2    6-1-2019     600            700
2   10-1-2019             500    200
3    2-2-2019     300            500
3   10-2-2019             300    200

更新

我正在使用@Gordon Linoff 代码

select b.*,
   (@b := @b + coalesce(debit, 0) - coalesce(credit, 0)) as balance from (select id, date, debit, credit
  from ((select id, date, debit, "0" as credit
         from debit
        ) union all
        (select id, date, "0" as debit, credit
         from credit 
        )
       ) b
  order by date
 ) b CROSS join
 (select @b := 0) params

它工作但我得到这样的输出table

id     date      debit  credit  balance
1    2-1-2019     400            400
2    6-1-2019     600            1000
3    2-2-2019     300            1300
1    4-1-2019             300    1000
2   10-1-2019             500    500
3   10-2-2019             300    200

我需要在这里按日期对整个数据进行排序，因为您可以看到首先排序的借方表数据，然后是贷方表的数据

Answer 1

您可以使用union all 组合表格。在 MySQL 8+ 中，您可以使用累积和计算最后一列：

select id, date, debit, credit,
       sum( coalesce(debit, 0) - coalesce(credit, 0) ) over (order by date) as balance
from ((select id, date, debit, null as credit
       from debit
      ) union all
      (select id, date, null as debit, credit
       from credit 
      )
     ) b
order by date;

在早期版本中，您可以使用变量进行计算：

select b.*,
       (@b := @b + coalesce(debit, 0) - coalesce(credit, 0)) as balance
from (select id, date, debit, credit
      from ((select id, date, debit, null as credit
             from debit
            ) union all
            (select id, date, null as debit, credit
             from credit 
            )
           ) b
      order by date
     ) b cross join
     (select @b := 0) params
order by date;