sql - 选择各自父记录中的子记录总数

Question

我有一个具有父子关系的会计科目表(层次结构模型)。 该表包含两种类型的帐户:控制帐户和交易帐户。

交易账户有余额，但不带有任何子账户。

控制账户没有自己的余额，但有子账户。

---

AccountID|     Title      |AccountType|ParentID| Balance
---------|----------------|-----------|--------|---------
 1       | Assets         |     c     |  null  | null 
 1-1     | Current Assets |     c     |  1     | null
 1-1-1   | Cash           |     t     |  1-1   | 1000
 1-1-2   | Inventory      |     t     |  1-1   | 2000
 1-2     | Fixed Assets   |     c     |  1     | null
 1-2-1   | Furniture      |     t     |  1-2   | 1500
 1-2-2   | Building       |     t     |  1-2   | 3000

---

我需要一个像这样的结果集:

---

AccountID|     Title      |AccountType|ParentID| Balance
---------|----------------|-----------|--------|---------
 1       | Assets         |     c     |  null  | 7500 --sum of current and fixed Assets
 1-1     | Current Assets |     c     |  1     | 3000 --sum of cash and inventory
 1-1-1   | Cash           |     t     |  1-1   | 1000
 1-1-2   | Inventory      |     t     |  1-1   | 2000
 1-2     | Fixed Assets   |     c     |  1     | 4500 --sum of furniture and building
 1-2-1   | Furniture      |     t     |  1-2   | 1500
 1-2-2   | Building       |     t     |  1-2   | 3000

---

交易表

---

ID |AccountID|Amount
---|---------|------
 1 | 1-1-1   |  300  
 2 | 1-1-1   |  700
 3 | 1-1-2   | 1500
 4 | 1-1-2   |  500
 5 | 1-2-1   |  700
 6 | 1-2-1   |  800
 7 | 1-2-2   | 2000
 8 | 1-2-2   | 1000

任何 select 语句(如果可能) 或函数或存储过程。

任何帮助将不胜感激

Answer 1

方法 1(感谢 asantaballa 将我的注意力转移到 CTE)

With TrialBalance(AccountID, ParentID, Balance)
AS
(
Select AccountId, ParentID, Balance From Accounts Where AccountType = 't'
Union All
Select A.AccountId, A.ParentID, T.Balance From Accounts A
Inner Join TrialBalance T On A.AccountId = T.ParentID
)
Select AccountID, SUM(Balance) From TrialBalance Group By AccountID    

方法2

Create Function AccountBalance(@AccountID Nvarchar(100))
Returns Float
AS
Begin
Declare @Balance Float
Select @Balance = Balance From Accounts Where AccountID = @AccountID
Select @Balance += Sum(dbo.AccountBalance(AccountID)) From Accounts
Where ParentID = @AccountID
Return @Balance
End

Select AccountID, dbo.AccountBalance(AccountID) From Accounts

以上两种方法都返回所需的结果。