对 GROUP BY 结果进行分组

Question

我有一个问题：

Select 
    (coalesce(sum(Ledger.Debit), 0) - coalesce(sum(Ledger.Credit), 0))   
    + Accounts.PreviousBalance  [Balance] 
FROM 
    Accounts
LEFT join 
    Ledger on Accounts.ID = Ledger.AccountId
Where 
    Accounts.Status = 'Active'
GROUP BY 
    Accounts.ID, Accounts.PreviousBalance

它 returns 23 行的所有账户摘要表明有多少客户必须 支付(-ve) 和 接收(+ve) 每个账户：

Balance
=========
800655.00
1869213.50
-6365.25
1148160.00
145743.70
804225.00
157625.00
66440.00
972950.00
780063.50
646680.75
277761.00
347100.00
-70882.50
-7435.50
431940.00
1319340.00
245685.00
372400.00
158220.00
608108.00
6777029.00
1147920.00

现在我想对这个总结做个总结。支付多少和获得多少累计值。例如：

Summary
===========
-84683.25      //sum of all negative values
19077259.45    //sum of all positive values

我是这样做的：

SELECT SUM([Balance]) as [Summary]
From 
(
    SELECT CASE WHEN [Balance] > 0 THEN 'Receieve' ELSE 'Pay' END AS 'Type', [Balance]
    From 
    (
        SELECT --Accounts.ID,
            -- ( Debit - Credit ) + Previous balance = balance
        (coalesce(sum(Ledger.Debit), 0) - coalesce(sum(Ledger.Credit), 0))   
        + Accounts.PreviousBalance  [Balance]
        FROM Accounts
        LEFT join Ledger ON Accounts.ID = Ledger.AccountId
        WHERE Accounts.Status = 'Active'
        GROUP BY Accounts.ID, Accounts.PreviousBalance
    ) as accountsSummary
) as summary
GROUP BY [Type]

但我知道这不是好的优化方式。这是一些混乱的嵌套子查询方法。必须有更清洁或更好的方法来做到这一点。如何用更好的方法实现它？

Answer 1

试一试：

WITH Balances
AS (
    SELECT 
        (coalesce(sum(Ledger.Debit), 0) - coalesce(sum(Ledger.Credit), 0)) + Accounts.PreviousBalance  [Balance] 
    FROM 
        Accounts
    LEFT join 
        Ledger on Accounts.ID = Ledger.AccountId
    Where 
        Accounts.Status = 'Active'
    GROUP BY 
        Accounts.ID, Accounts.PreviousBalance
),
Receipts AS (
    SELECT SUM(Balance) Balance
    FROM Balances
    WHERE Balance > 0
),
Payments AS (
    SELECT SUM(Balance) Balance
    FROM Balances
    WHERE Balance < 0
)    
SELECT Balance FROM Receipts 
UNION 
SELECT Balance FROM Payments

Answer 2

你为什么不使用 LINQ。首先使用 SQL 获取全部数据。然后使用 c#（使用 LINQ）查询它。会容易很多。

Answer 3

在外部查询中，只需区分 positive 值和 group by 中的 negative 值，这就是您所需要的

WITH Balances
AS (
    SELECT 
        (coalesce(sum(Ledger.Debit), 0) - coalesce(sum(Ledger.Credit), 0)) + Accounts.PreviousBalance  [Balance] 
    FROM 
        Accounts
    LEFT join 
        Ledger on Accounts.ID = Ledger.AccountId
    Where 
        Accounts.Status = 'Active'
    GROUP BY 
        Accounts.ID, Accounts.PreviousBalance
),
select SUM(Balance)
from Balances
group by case when Balance < 0 then 1 else 0 end