Question

我有一个包含“余额”列的表格，其中存储了每个客户帐户（Account_id）的最新余额。现在我想自动增加对年度余额的兴趣，并且在完成每一年后，应该在新的余额中添加利息。我怎么能用VB.Net（Visual Studio 2008）和Sql Server（Express版本）做到这一点？

表名是Deposit。列是这样的：

Trans_id Acc_id Trans_date 金额余额

Answer 1

我相信这是你正在寻找的。我不得不在帐户表中添加一个列，我假设有一个客户表，其中包含＆＃34;出生日期＆＃34;。

declare @customer table(
  [acc_id]    [int] identity(1, 1)
  , [name]    [sysname]
  , [created] [datetime] default dateadd(year, -1, current_timestamp));
insert into @customer
        ([name])
values      (N'joe'),
        (N'sally');
--
declare @account table (
  [trans_id]         [int] identity(1, 1)
  , [acc_id]         [int]
  , [trans_date]     [datetime] default current_timestamp
  , [amount balance] [money]
  , [interest_paid]  [datetime] null);
insert into @account
        ([acc_id],[amount balance])
values      (1,N'25.00'),
        (2,N'50.00');
--
declare @interest [float] = 0.03;
update @account
set    [amount balance] = [amount balance] + ( [amount balance] * @interest )
   , [interest_paid] = current_timestamp
from   @account as [account]
   join @customer as [customer]
     on [customer].[acc_id] = [account].[acc_id]
where  ( datediff(day
              , [interest_paid]
              , current_timestamp) >= 365
      or [interest_paid] is null )
   and datediff(day
                , [customer].[created]
                , current_timestamp) >= 365;
--
select * from   @account as [account]
   join @customer as [customer]
     on [customer].[acc_id] = [account].[acc_id];
--
-- this should not update as the [interest_paid] date is less than one year old
update @account
set    [amount balance] = [amount balance] + ( [amount balance] * @interest )
   , [interest_paid] = current_timestamp
from   @account as [account]
   join @customer as [customer]
     on [customer].[acc_id] = [account].[acc_id]
where  ( datediff(day
              , [interest_paid]
              , current_timestamp) >= 365
      or [interest_paid] is null )
   and datediff(day
                , [customer].[created]
                , current_timestamp) >= 365;
--
select *
from   @account as [account]
       join @customer as [customer]
         on [customer].[acc_id] = [account].[acc_id];
--
declare @future [datetime] = dateadd(year
          , 1
          , current_timestamp);
--
-- this SHOULD update as the [interest_paid] date is a year old based on the future date
update @account
set    [amount balance] = [amount balance] + ( [amount balance] * @interest )
       , [interest_paid] = @future
from   @account as [account]
       join @customer as [customer]
         on [customer].[acc_id] = [account].[acc_id]
where  ( datediff(day
                  , [interest_paid]
                  , @future) >= 365
          or [interest_paid] is null )
       and datediff(day
                    , [customer].[created]
                    , @future) >= 365;
--
select *
from   @account as [account]
       join @customer as [customer]
         on [customer].[acc_id] = [account].[acc_id];

如何自动计算兴趣并使用SQL和VB.NET将其添加到每个account_id（行）

1 个答案: