连接表 - 如何汇总问题（总和）？

Question

我有两个这样连接的表：

SELECT count(DISTINCT T1.ContractNumber) AS nr_of_contracts,
       count(T3.DateofInstallmentPayment) AS nr_of_paid_installents, 
       count(T3.DateofDueInstallment) AS nr_of_installments, 
       sum(T1.DisbursementAmount) AS disbursed_amount

FROM q.T1
LEFT JOIN q.T3
ON T1.ContractNumber=T3.ContractNumber

WHERE   DateOfDisbursement BETWEEN '2019-12-01' AND '2019-12-31'
        AND T3.DateofDueInstallment < GETDATE()

其中 T1 表包含有关客户的数据（按合同编号），T3 包含有关其付款计划的数据（按每期付款）。

我想要的是从表 T1（按合同编号汇总）中支付合同的金额（支付金额），而不是按每期付款。当我尝试只选择 sum(T1.Disbursement amount) 时，我收到了 sum，但所有分期付款都不正确。

T1：

Contract Number	DisbursementDate	Disbursement Amount
1	2019-12-01	1000
2	2019-12-01	2000
3	2019-12-01	3000

T3：

Contract Number	DateofDueInstallment	DateofInstallmentPayment
1	2020-01-01	2020-01-01
1	2020-02-01	2020-02-06
1	2020-03-01	2020-04-01

在为 Contract Number = 1 加入两个表后，我得到的是 sum(DisbursementAmount) = 3000。

Contract Number	sum(DisbursementAmount)
1	3000

在为 Contract Number = 1 加入两个表后，我想要的是 sum(DisbursementAmount) = 1000。

Contract Number	sum(DisbursementAmount)
1	1000

Answer 1

类似的东西，未经测试 - 具有不同聚合列的子查询

SELECT T1.product, T1.NrOfInstallment, count(DISTINCT T1.ContractNumber), 
           SELECT paid_amound FROM(SELECT ContractNumber, sum(tt.DisbursementAmount + (tt.ContractNumber*0.01))  
                    - sum(tt.ContractNumber*0.01) as paid_amount
    FROM abc.T1 as tt  WHERE tt.ContractNumber = T1.ContractNumber GROUP BY ContractNumber) AS t)                           
    FROM abc.T1
    LEFT JOIN bde.T3
    ON T1.ContractNumber=T3.ContractNumber
    GROUP BY T1.product, T1.NrOfInstallment