利用数据库触发器让字段与自增长Id相关联

时间：2018-04-27 12:27:29 阅读：202 评论：0 收藏：0 [点我收藏+]

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今天是数据库脚本类的代码，所以不想过多阐述

如下数据表：

create table Card(
Id int identity(1,1) primary key,
CardNo varchar(50) unique not null,
Status bit default(0)
)

上述表中有自增长字段Id，现在要求字段 CardNo 和自增长Id 相关联，譬如，当Id为1时，CardNo 应该为 Card00001，当Id为15时，CardNo应该为： Card00015 ，要求通过触发器或存储过程实现？

其中触发器实现如下：

create TRIGGER [dbo].[TGR_Card] 
   ON  [dbo].[Card] 
   AFTER INSERT
AS 
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;

    -- Insert statements for trigger here、
    DECLARE    @Id    bigint
    SELECT    @Id = Id FROM    INSERTED

    UPDATE    Card
    SET        CardNo =    CASE
                                        WHEN LEN(@Id) = 1 THEN  ‘Crad0000000‘ + CAST(@Id AS varchar(20))
                                        WHEN LEN(@Id) = 2 THEN  ‘Crad000000‘ + CAST(@Id AS varchar(20))
                                        WHEN LEN(@Id) = 3 THEN  ‘Crad00000‘ + CAST(@Id AS varchar(20))
                                        WHEN LEN(@Id) = 4 THEN  ‘Crad0000‘ + CAST(@Id AS varchar(20))
                                        WHEN LEN(@Id) = 5 THEN  ‘Crad000‘ + CAST(@Id AS varchar(20))
                                        WHEN LEN(@Id) = 6 THEN  ‘Crad00‘ + CAST(@Id AS varchar(20))
                                        WHEN LEN(@Id) = 7 THEN  ‘Crad0‘ + CAST(@Id AS varchar(20))
                                        WHEN LEN(@Id) = 8 THEN  ‘Crad‘ + CAST(@Id AS varchar(20))                                                                                
                                    END 
    WHERE orderId = @Id        

END