关于数据库字段重复时,名称自动加1的问题
之前项目(类似网盘类的系统)中遇到的一个问题,每次创建一个新文件夹时在新文件夹(+1递增),我的解决方案是在数据库表中加触发器,这能减少代码的开发量,不用书写代码逻辑
触发器如下:
CREATE trigger [dbo].[tr_folder_after] on [dbo].[storage_FolderUser] after insert as --@count:同名文件夹的个数,@newname新文件夹的名称 declare @count int,@newname nvarchar(20),@id int,@parentid int,@name nvarchar(20),@creator int; select @id=id,@parentid=FolderID,@name=Name,@creator=Creator from Inserted; select @count=count(ID) from [dbo].[storage_FolderUser] where Creator=@creator AND FolderID=@parentid AND Name=@name if @count>1 begin set @newname=@name; set @count=0; while @count>=0 begin if exists(select * from [dbo].[storage_FolderUser] where Creator=@creator AND FolderID=@parentid AND Name=@newname) begin set @count=@count+1; set @newname=@name+'('+convert(varchar, @count)+')'; end else begin set @count=-1; end end UPDATE [dbo].[storage_FolderUser] SET Name=@newname WHERE ID=@id; end
结果如下:
将 新建文件夹(1) delete 后,再次执行插入数据后将依然按增长顺序补上
delete from [dbo].[storage_FolderUser] where id=2 insert into [dbo].[storage_FolderUser](FolderID,Name,Creator,Created)values(0,'新建文件夹',626,getdate())