基于在SQL Server中返回的查询的更新表

Question

我遇到了更新查询。我有一个查询为

SELECT s_no, loan_id,repayment_date,principal,loan_balance, count(*) as repeatTimes 
FROM loan_repayment_plan_mcg 
GROUP BY s_no, loan_id, repayment_date,principal,loan_balance 
HAVING count(*) > 1 

它返回的输出：

s_no loan_id repayment_date principal loan_balance repeatTimes 
1   21111 2012-03-13   0.00 5000.00   2 
2   21311 2012-04-12   0.00 2000.00   2 
3   21111 2012-05-13   500  5000.00   2 
4   21111 2012-06-14   0.00 5000.00   3 

我想更新loan_balance从我上面的选择查询乘以repeatTimes基于loan_id和repayment_date它结合在一起，使一个唯一的行。

Answer 1

的传统方法，使用UPDATE从JOIN

update A 
set loan_balance = loan_balance * repeatTimes 
from loan_repayment_plan_mcg A 
join 
(
SELECT s_no, loan_id,repayment_date,principal,loan_balance, count(*) as repeatTimes 
FROM loan_repayment_plan_mcg 
GROUP BY s_no, loan_id, repayment_date,principal,loan_balance 
HAVING count(*) > 1 
) B on A.s_no = B.s_no 
    and A.loan_id = B.loan_id 
    and A.repayment_date = B.repayment_date 
    and A.principal = B.principal 
    and A.loan_balance = B.loan_balance; 

在SQL Server中使用窗函数和CTE 2008

;with cte as (
    SELECT *,sum(loan_balance) over (
      partition by s_no,loan_id,repayment_date,principal,loan_balance) total_balance 
    FROM loan_repayment_plan_mcg 
) 
update cte 
    set loan_balance = total_balance 
where loan_balance != total_balance;