实现记录排序

以前曾经在asp.net实现记录排序功能，参考：http://www.cnblogs.com/insus/articles/1406440.html前端实现，写得很复杂。

现在，把它改为触发器来实现，那就简单多了。由于时隔已久，原实例样版代码已经找不到了，只有再写一样功能一样的表。这个表实现与记录插入功能，可以参考相关链接：

http://www.cnblogs.com/insus/articles/1921391.html

http://www.cnblogs.com/insus/articles/1921465.html

http://www.cnblogs.com/insus/articles/1921618.html

http://www.cnblogs.com/insus/articles/1922387.html

 

完整记录排序触发器代码(更新记录)，

代码

SET  ANSI_NULLS  ON
GO
SET  QUOTED_IDENTIFIER  ON
GO

IF   EXISTS  ( SELECT   [ name ]   FROM  sysobjects  WHERE   [ name ]   =   ' tri_OrderDemo_Update '   AND  TYPE  =   ' TR ' )
    DROP   TRIGGER   [ dbo ] . [ tri_OrderDemo_Update ]
GO

CREATE   TRIGGER   [ dbo ] . [ tri_OrderDemo_Update ]   ON   [ dbo ] . [ OrderDemo ]
FOR   UPDATE
AS
-- 宣告变量,存储更新记录的主键，[Num]字段的旧值，新值，以及所有记录的[Num]字段的最大值与最小值，最小值设为1
DECLARE   @PK   INT , @OldValue   INT ,  @NewValue   INT , @MaxValue   INT , @MinValue   INT   =   1
-- 从deleted虚拟表找主键和[Num]字段到旧值
SELECT   @PK   =   [ OrderDemoId ] , @OldValue   =   [ Num ]   FROM  deleted
-- 从inserted虚拟表找[Num]字段到新值
SELECT   @NewValue   =   [ Num ]   FROM  inserted 
-- 从表[OrdeDemo]找到最大值
SELECT   @MaxValue   =   MAX ( [ Num ] )  FROM   [ dbo ] . [ OrderDemo ]


BEGIN     
     -- 由大的排序号，排至小的排序号
      IF  ( @NewValue   <   @OldValue )
         UPDATE   [ dbo ] . [ OrderDemo ]   SET   [ Num ]   =   [ Num ]   +   1   WHERE   [ OrderDemoId ]   IN  ( SELECT   [ OrderDemoId ]   FROM   [ dbo ] . [ OrderDemo ]   WHERE   [ Num ]   BETWEEN   @NewValue   AND  ( @OldValue   -   1 ))  AND   [ OrderDemoId ]   <>   @PK
     -- 由小的排序号，排至大的排序号
     ELSE   IF  ( @NewValue   >   @OldValue )
         UPDATE   [ dbo ] . [ OrderDemo ]   SET   [ Num ]   =   [ Num ]   -   1   WHERE   [ OrderDemoId ]   IN  ( SELECT   [ OrderDemoId ]   FROM   [ dbo ] . [ OrderDemo ]   WHERE   [ Num ]   BETWEEN  ( @OldValue   +   1 )  AND   @NewValue )  AND   [ OrderDemoId ]   <>   @PK
     ELSE
       -- 新值与旧值一样，不作更新@NewValue = @OldValue      
       RETURN
END

 

 删除记录触发器，

代码

SET  ANSI_NULLS  ON
GO
SET  QUOTED_IDENTIFIER  ON
GO
IF   EXISTS  ( SELECT   [ name ]   FROM  sysobjects  WHERE   [ name ]   =   ' tri_OrderDemo_Delete '   AND  TYPE  =   ' TR ' )
    DROP   TRIGGER   [ dbo ] . [ tri_OrderDemo_Delete ]
GO


CREATE   TRIGGER   [ dbo ] . [ tri_OrderDemo_Delete ]   ON   [ dbo ] . [ OrderDemo ]
FOR   DELETE
AS
-- 宣告变量,存储删除记录的[Num]字段的值
DECLARE   @Value   INT , @MaxValue   INT
-- 从deleted虚拟表找主键和[Num]字段值
SELECT   @Value   =   [ Num ]   FROM  deleted
SELECT   @MaxValue   =   MAX ( [ Num ] )  FROM   [ dbo ] . [ OrderDemo ]

BEGIN         
      IF  ( @Value   <   @MaxValue )
         UPDATE   [ dbo ] . [ OrderDemo ]   SET   [ Num ]   =   [ Num ]   -   1   WHERE   [ OrderDemoId ]   IN  ( SELECT   [ OrderDemoId ]   FROM   [ dbo ] . [ OrderDemo ]   WHERE   [ Num ]   BETWEEN   @Value   +   1   AND   @MaxValue )
END