如何动态地从两个SQL表debit和credit中获取平衡

客户表

id |    name      |  customerid 
1  | Philip James |   ac1001 
2  | Frank Mathew |   ac1002   

信用表

id| year  | customer |  amount  
1 | 2020  | ac1001   |  1000
2 | 2020  | ac1001   |  1000
3 | 2020  | ac1001   |  1000
4 | 2020  | ac1001   |  1000
5 | 2019  | ac1001   |  1000
6 | 2019  | ac1001   |  2000
7 | 2020  | ac1002   |  2000
8 | 2020  | ac1002   |  2000

借记表

id| year |  customer|   amount  
1 | 2020 |  ac1001  |   1000
2 | 2020 |  ac1001  |   1000
3 | 2020 |  ac1001  |   1000
4 | 2020 |  ac1001  |   1000
5 | 2019 |  ac1001  |   2000
6 | 2019 |  ac1001  |   2000
7 | 2020 |  ac1002  |   2000
8 | 2020 |  ac1002  |   2000

我试图动态地获得每个客户在这一年的余额，我尝试使用这个； SELECT debit.year,customers.name,customers.customerid,SUM(debit.amount),SUM(credit.amount), SUM(COALESCE((debit.amount),0)-COALESCE((credit.amount),0))AS balance FROM customers RIGHT JOIN credit ON customers.customerid=credit.customer RIGHT JOIN debit ON customers.customerid=debit.customer GROUP BY customers.customerid,debit.year 但我需要的是下表，谢谢

预期结果

year|   customer |  sum(debit)| sum(credit)| Balance    
2019 |  ac1001   |  4000      | 3000       | 1000
2020 |  ac1001   |  4000      | 4000       |  0
2020 |  ac1002   |  4000      | 4000       |  0

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联合

两个表，然后进行聚合。您可以使用累计总和来计算余额：

select year, customer, sum(amount) as amount_in_year,
       sum(sum(amount)) over (partition by customer order by year) as end_of_year_balance
from ((select id, year, customer, amount
       from credit
      ) union all
      (select id, year, customer, - amount
       from debit
      ) 
     ) cd
group by year, customer;

编辑：

经修订的问题：

select year, customer, sum(credit) as sum_credit, sum(debit) as sum_debit,
       sum(sum(credit - debit)) over (partition by customer order by year) as end_of_year_balance
from ((select id, year, customer, amount as credit, 0 as debit
       from credit
      ) union all
      (select id, year, customer, 0 as credit, amount as debit
       from debit
      ) 
     ) cd
group by year, customer;

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我还有一个问题，贷方表和借方表中的个人金额没有显示出来，我能得到一些帮助吗that@SamuelMomoh . . . 这是相同的想法，只是更多的专栏。

select year, customer, sum(credit) as sum_credit, sum(debit) as sum_debit,
       sum(sum(credit - debit)) over (partition by customer order by year) as end_of_year_balance
from ((select id, year, customer, amount as credit, 0 as debit
       from credit
      ) union all
      (select id, year, customer, 0 as credit, amount as debit
       from debit
      ) 
     ) cd
group by year, customer;