Question

我需要将两行相互比较，然后将更改的字段写入表中。

我的表：

CREATE TABLE dbo.tUserChanges
(
cID int IDENTITY (1,1),
cChangeDate DateTime,
cValueChanged varchar(30),
cPreviousValue bit,
cCurrentValue bit
)

在我的C＃程序中，当对用户进行更改时，需要更新用户表。

这是通过存储过程完成的：

CREATE PROCEDURE [dbo].[UUser]       
( 
 @User as varchar(15),   
 @UCode  AS int,      
 @UName  AS varchar(30),      
 @UID   AS  varchar(10),      
 @UPassword  AS varchar(15),      
 @UPMaintenance as bit,      
 @UClient  as bit,      
 @UFinancial  as bit,      
 @UViewReceiptImage bit,
 @UViewPayrollData bit
) 
AS
BEGIN
UPDATE  tUsers      
 SET        
 UName    = @UName,      
 UID    = @UID,      
 UPassword   = @UPassword,  UPMaintenance   = @UPMaintenance,       
 UClient    = @UClient,      
 UFinancial   = @UFinancial,
 UViewReceiptImage = @UViewReceiptImage,
 UViewPayrollData = @UViewPayrollData     
 WHERE UCode = @UCode 
END

tUser表中有更多值，但为了保持排序，我删除了一些值。

所以我需要做的是在befor更新tUsers表时创建一个临时表，这样我就可以在更新完成后比较两行，然后将发生的更改改为新表。 / p>

我试过这个，但我知道有更好的方法，它也没有给出所需的结果：

declare @i int
set @i = 0
declare @ColumnCount int
set @ColumnCount = (SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS WHERE  table_name = @UID)
declare @ColumnName varchar(30)
set @ColumnName = (select column_name from information_schema.columns  where table_name = 'tUsers' and ordinal_position = 14)

select UActivateLoan from tusers

while (@ColumnCount < @i)
Begin
    if((select @ColumnName from tUsers where UID = @UID) 
    <> (select @ColumnName from #myTemp where UID = @UID))
    Begin
        Insert into tUserChanges
        Values(GETDATE(),(select column_name from information_schema.columns  where table_name = 'tUsers' and ordinal_position = 14),
                (select(select column_name from information_schema.columns  where table_name = 'tUsers' and ordinal_position = 14) from #myTemp where UID = @UID),
                (select(select column_name from information_schema.columns  where table_name = 'tUsers' and ordinal_position = 14) from tUsers where UID = @UID))
    END
    set @i = @i + 1
End

我不确定我是否需要在这里使用光标或我可以做些什么来获得结果？任何帮助将不胜感激。

Answer 1

使用FOR UPDATE触发器可以做得更好。

CREATE TRIGGER dbo.tUser_AfterUpdate ON dbo.tUsers FOR UPDATE AS 
BEGIN
  IF UPDATE(UName) THEN 
    INSERT INTO tUserChanges 
    SELECT GETDATE()
           , (SELECT UName FROM DELETED) -- Old Value
           , (SELECT UName FROM INSERTED) -- New Value

  ...
END

CREATE TRIGGER

创建一个触发器，它是一种特殊的存储过程当用户尝试指定时自动执行指定表上的数据修改语句。 Microsoft®SQL Server™允许为任何给定的INSERT创建多个触发器， UPDATE或DELETE语句。

修改

使用动态SQL，就像

CREATE TRIGGER dbo.tUser_AfterUpdate ON dbo.tUsers FOR UPDATE AS BEGIN DECLARE @Columns TABLE (name sysname) DECLARE @ColumnName sysname DECLARE @Statement VARCHAR(MAX) INSERT INTO @Columns SELECT name FROM sys.columns WHERE OBJECT_NAME(OBJECT_ID) = 'tUsers' WHILE EXISTS (SELECT * FROM @Columns) BEGIN SELECT TOP 1 @ColumnName = name FROM @Columns DELETE FROM @Columns WHERE name = @ColumnName SET @Statement = 'IF UPDATE(' + @ColumnName + ') THEN ' + 'INSERT INTO tUserChanges ' + 'SELECT GETDATE() ' + ' , (SELECT ' + @ColumnName + 'FROM DELETED) -- Old Value' + ' , (SELECT ' + @ColumnName + 'FROM INSERTED) -- New Value' EXEC (@Statement) END END

需要比较两行的差异吗？

1 个答案: