如何从子表中的另一行有条件地获取值

Question

root@debianlpi:~# cat /etc/apt/apt.conf
#Acquire::http::Proxy "http://idcproxy.compabc.com:80";

我的目标是使用Select * from LoanAccount main INNER JOIN LoanSubAccount sub WHERE main.LoanAccountID = sub.LoanAccountID AND sub.LoanStatus = 4 检索行，但使用LoanStatus = 4的记录替换金额。 最终结果预计为

Answer 1

WITH cte AS (
    SELECT *,
           ROW_NUMBER() OVER (PARTITION BY LoanAccountID, LoanStatus
                              ORDER BY LoanSubAccountID) rn
    FROM LoanSubAccount
)
SELECT t1.LoanSubAccountID,
       t1.LoanAccountID,
       t1.LoanStatus,
       t1.CommodityType,
       t2.Amount
FROM cte t1
INNER JOIN cte t2
    ON t1.rn = t2.rn AND
       t1.LoanStatus > t2.LoanStatus

我宁愿展示一张代表上述CTE外观的表格，而不是给出详细的解释：

rn | LoanSubAccountID | LoanAccountID | LoanStatus | CommodityType | Amount
1  | 1                | 1             | 2          | 1             | 100
2  | 2                | 1             | 2          | 2             | 200
1  | 3                | 1             | 4          | 3             | 150
2  | 4                | 1             | 4          | 4             | 150

如果我正确阅读了您的要求，您希望从两种不同的贷款状态中连接具有相同行号的行。我上面给出的连接查询就是这样做的。