Question

希望对于那些在SQL Server中经验丰富的人来说这很容易。

我有一个客户贷款活动数据表，每当他们的帐户发生操作时都会更新。例如，如果增加其限制，将使用新限制创建新记录。我希望能够创建活动列表，其中活动金额是他们的新限制，减去他们之前的限制。

目前我有以下内容，但我正在努力研究如何访问之前的记录。

SELECT   
    CUSTOMER
    ,LEDGER
    ,ACCOUNT
    ,H.AMOUNT - COALESCE(X.AMOUNT, 0)
FROM 
    dbo.ACTIVITY H WITH (NOLOCK)
LEFT OUTER JOIN 
    (SELECT  
        CUSTOMER
        ,LEDGER
        ,ACCOUNT
        ,ACTIVITY_DATE
        ,AMOUNT
        ,ROW_NUMBER() OVER (PARTITION BY CUSTOMER, LEDGER, ACCOUNT ORDER BY ACTIVITY_DATE ASC) AS ROW_NUMBER
     FROM 
         dbo.ACTIVITY WITH (NOLOCK)) X ON H.CUSTOMER = X.CUSTOMER
                                          AND H.LEDGER = X.LEDGER
                                          AND H.ACCOUNT = X.ACCOUNT

所以基本上我只想减去x.amount，如果它是以前的记录，但是当我不知道它发生在哪一天时我不知道该怎么做。

我认为Row_Number()会帮助我，但我仍然有点难过。

希望你很快收到你的消息：）

干杯

Answer 1

以下是仅通过dbo.Activity ONCE

的查询

    SELECT H.CUSTOMER
          ,H.LEDGER
          ,H.ACCOUNT
          ,MAX(H.ACTIVITY_DATE) ACTIVITY_DATE
          ,SUM(CASE X.I WHEN 1 THEN AMOUNT ELSE -AMOUNT END) AMOUNT
      FROM (SELECT CUSTOMER
                  ,LEDGER
                  ,ACCOUNT
                  ,ACTIVITY_DATE
                  ,AMOUNT
                  ,ROW_NUMBER() OVER (PARTITION BY CUSTOMER, LEDGER, ACCOUNT ORDER BY ACTIVITY_DATE DESC) AS ROW_NUMBER
             FROM dbo.ACTIVITY WITH (NOLOCK)
           ) H
CROSS JOIN (select 1 union all select 2) X(I)
     WHERE ROW_NUMBER - X.I >= 0
  GROUP BY H.CUSTOMER
          ,H.LEDGER
          ,H.ACCOUNT
          ,ROW_NUMBER - X.I;

这是我用来测试的一些数据的DDL / DML

CREATE TABLE dbo.ACTIVITY(CUSTOMER int, LEDGER int, ACCOUNT int, ACTIVITY_DATE datetime, AMOUNT int)
INSERT dbo.ACTIVITY select
    1,2,3,GETDATE(),123 union all select
    1,2,3,GETDATE()-1,16 union all select
    1,2,3,GETDATE()-2,12 union all select
    1,2,3,GETDATE()-3,1 union all select
    4,5,6,GETDATE(),1000 union all select
    4,5,6,GETDATE()-6,123 union all select
    7,7,7,GETDATE(),99;

替代

使用子查询获取前一行的更传统的方法：

  SELECT CUSTOMER, LEDGER, ACCOUNT, ACTIVITY_DATE,
         AMOUNT - ISNULL((SELECT TOP(1) I.AMOUNT
                            FROM dbo.ACTIVITY I
                           WHERE I.CUSTOMER = O.CUSTOMER
                             AND I.LEDGER = O.LEDGER
                             AND I.ACCOUNT = O.ACCOUNT
                             AND I.ACTIVITY_DATE < O.ACTIVITY_DATE
                        ORDER BY I.ACTIVITY_DATE DESC), 0) AMOUNT
    FROM dbo.ACTIVITY O
ORDER BY CUSTOMER, LEDGER, ACCOUNT, ACTIVITY_DATE;

或者ROW_NUMBER（）数据两次并在它们之间加入

   SELECT A.CUSTOMER, A.LEDGER, A.ACCOUNT, A.ACTIVITY_DATE, 
          A.AMOUNT - ISNULL(B.AMOUNT,0) AMOUNT
     FROM (SELECT *, RN=ROW_NUMBER() OVER (partition by CUSTOMER, LEDGER, ACCOUNT
                                          order by ACTIVITY_DATE ASC)
            FROM dbo.ACTIVITY) A
LEFT JOIN (SELECT *, RN=ROW_NUMBER() OVER (partition by CUSTOMER, LEDGER, ACCOUNT
                                          order by ACTIVITY_DATE ASC)
            FROM dbo.ACTIVITY) B ON A.CUSTOMER = B.CUSTOMER
                              AND A.LEDGER = B.LEDGER
                              AND A.ACCOUNT = B.ACCOUNT
                              AND B.RN = A.RN-1 -- prior record
ORDER BY A.CUSTOMER, A.LEDGER, A.ACCOUNT, A.ACTIVITY_DATE;

在SQL Server中使用ROW_NUMBER（）获取上一条记录的值

1 个答案:

替代