Question

这是我的sql代码：

CREATE TABLE #tmp
    (
      Id INT IDENTITY(1, 1) ,
      Amount MONEY ,
      Rate FLOAT ,
      NetAmount MONEY
    );
CREATE TABLE #rate ( Rate FLOAT );
INSERT  INTO #rate
        ( Rate )
VALUES  ( 1.2 );
  -- Rate - float

INSERT  INTO #rate
        ( Rate )
VALUES  ( 1.3  -- Rate - float
          );

INSERT  INTO #rate
        ( Rate )
VALUES  ( 1.5  -- Rate - float
          );
DECLARE @Amount MONEY = 5000;
INSERT  INTO #tmp
        ( Amount ,
          Rate ,
          NetAmount
        ) 
        SELECT  @Amount ,
                r.Rate ,
                r.Rate * @Amount
        FROM    #rate AS r;


SELECT  *
FROM    #tmp AS t;

DROP TABLE #rate;
DROP TABLE #tmp;

这是我的输出：

Id          Amount                Rate                   NetAmount
----------- --------------------- ---------------------- ---------------------
1           5000.00               1.2                    6000.00
2           5000.00               1.3                    6500.00
3           5000.00               1.5                    7500.00

我需要这样的输出：

Id          Amount                Rate                   NetAmount
    ----------- --------------------- ---------------------- ---------------------
    1           5000.00               1.2                    6000.00
    2           6000.00               1.3                    7800.00
    3           7800.00               1.5                    11700.00

正如您所看到的，第一个金额5000.00作为参数被接收，然后有一个按特定顺序定义的费率列表。我需要在你所需的输出中看到每个费率。第一个NetAmount成为下一行的金额。

我想在不使用游标或while循环的情况下实现此目的。

Answer 1

只需添加Computed column，然后将输出中的魔法视为

CREATE TABLE #tmp
    (
      Id INT IDENTITY(1, 1) ,
      Amount MONEY ,
      Rate FLOAT ,
      NetAmount AS Amount * Rate    -- computed column 
    );
CREATE TABLE #rate ( Rate FLOAT );
INSERT  INTO #rate
        ( Rate )
VALUES  ( 1.2 );
  -- Rate - float

INSERT  INTO #rate
        ( Rate )
VALUES  ( 1.3  -- Rate - float
          );

INSERT  INTO #rate
        ( Rate )
VALUES  ( 1.5  -- Rate - float
          );
DECLARE @Amount MONEY = 5000;
INSERT  INTO #tmp
        ( Amount ,
          Rate
          --, NetAmount
        ) 
        SELECT  @Amount ,
                r.Rate 
                --,r.Rate * @Amount
        FROM    #rate AS r;


SELECT  *
FROM    #tmp AS t;

DROP TABLE #rate;
DROP TABLE #tmp;

Answer 2

您需要累积的费率产品。但是，没有内置功能来实现这一点。您可以使用LOG和EXP以及累计SUM来实现此目的：

insert into #tmp (amount, rate, netamount)
select lag(netamount, 1, @Amount) over (order by id) as amount,
    rate,
    netamount
from (
    select id,
        @amount * exp(sum(log(rate)) over (order by id)) as netamount,
        rate
    from #rate
    ) t;

这假设您在费率表中有一个ID列，您想要按照其应用的费率和计算的金额。记住，RDBMS中没有内在的顺序。

如何将立即插入的行的列插入批量插入的下一列？

2 个答案: