C# 生成编号（防并发）

今天抽了点时间，写了一个通用的生成编号的程序！

我的生成规则为年月日+两位编号，即：yyyyMMdd+两位编号，譬如：2018101001 / 2018101002 / 2018101003

首先，一个项目中有很多表需要生成编号，譬如：产品编号，评估编号，学生学号等

下面看看我的思路，如下：

首先创建一张表，如下：

create table CM_CodeNo
(
Id int identity(1,1) primary key not null,
CodeCate varchar(50) not null unique,--现场考察 非设计类履约评估等
VersionNum TimeStamp not null,
CodeYear int,
CodeMonth int,
CodeDay int,
CodeValue varchar(20),
CodeCount int,
AddTime datetime default(getdate()),
)

简单解读下这张表的构造：

CodeCate：编号分类，譬如：产品编号、评估编号等

VersionNum：乐观锁版本号，用于处理并发，有兴趣的可参考鄙人的博客：https://www.cnblogs.com/chenwolong/p/BF.html#4094056

CodeYear：年

CodeMonth：月

CodeDay：日

CodeCount：代表今天生产了几个编号

AddTime：生产时间

CodeValue：无效字段，没用到...

表的解读就这么多，现在来看一组存储过程：

ALTER proc [dbo].[LockCodeNoProc] --
(
@CodeCate nvarchar(50), 
@IsSuccess bit=0 output
)
as
declare @currentYear as int 
declare @currentMonth as int 
declare @currentDay as int 
declare @count as int
declare @CodeCount as int
declare @flag as TimeStamp
declare @rowcount As int 

set @currentYear=DateName(year,GetDate()) 
set @currentMonth=DateName(month,GetDate()) 
set @currentDay=DateName(day,GetDate())
begin tran
select @count=count(1) from CM_Code where CodeYear=@currentYear and CodeMonth = @currentMonth and CodeDay=@currentDay and CodeCate=@CodeCate
if @count=0
begin
insert into CM_Code(CodeCate,CodeYear,CodeMonth,CodeDay,CodeValue,CodeCount,AddTime) 
values(@CodeCate,@currentYear,@currentMonth,@currentDay,'',1,GETDATE())
select CodeCount from  CM_Code where CodeYear=@currentYear and CodeMonth = @currentMonth and CodeDay=@currentDay and CodeCate=@CodeCate
end
else
begin
select @count=CodeCount,@flag=VersionNum from CM_Code where CodeYear=@currentYear and CodeMonth = @currentMonth and CodeDay=@currentDay and CodeCate=@CodeCate
--waitfor delay '00:00:10'  --可用于模拟并发
update CM_Code set CodeCount=@count+1 where VersionNum=@flag and CodeYear=@currentYear and CodeMonth = @currentMonth and CodeDay=@currentDay and CodeCate=@CodeCate
set @rowcount=@@ROWCOUNT
select CodeCount from  CM_Code where CodeYear=@currentYear and CodeMonth = @currentMonth and CodeDay=@currentDay and CodeCate=@CodeCate

if @rowcount>0
begin
set @IsSuccess=1
select @IsSuccess
end
else
begin
set @IsSuccess=0
select @IsSuccess
end
end
commit tran

调用这个存储过程，会返回当前分类今天生产的编号数量，

时间有限，不作过多解读，大家自行理解，

下面是C#代码：

    public class GetCode
    {
        public static string GetCodeNo(Enum CodeCate)
        {
            PortalCodeModel M = new PortalCodeModel();
            M = U_GetCode.GetCodeNo(CodeCate);
            //--模拟发生了并发，需要等待，重复请求，最大请求次数为10次
            int retry = 10;
            while (!M.IsSuccess && retry > 0)
            {
                retry--;
                GetCodeNo(CodeCate);
            }
            //
            string code = GetCodeString(M.Result);
            return code;

        }

        public static string GetCodeString(int CodeCount)
        {
            string initStr = DateTime.Now.ToString("yyyyMMdd");
            int initLen = initStr.Length;
            int Len = CodeCount.ToString().Length;
            int MaxLen = 10;
            string ling = string.Empty;
            int TotalLen = initLen + Len;
            if (TotalLen <= MaxLen)
            {
                switch (Len)
                {
                    case 1:ling = initStr + "0" + CodeCount.ToString();break;
                    default: ling = initStr + CodeCount.ToString(); break;
                }
            }
            return ling;
        }
    }

DAL层如下：

        public static PortalCodeModel GetCodeNo(Enum CodeCate)
        {
            using (DataAccessBroker broker = DataAccessFactory.Instance())
            {
                PortalCodeModel M = new PortalCodeModel();
                DataAccessParameterCollection parameters = new DataAccessParameterCollection();
                parameters.AddWithValue("@CodeCate", CodeCate.ToString());
                parameters.AddWithValue("@IsSuccess", ParameterDirection.ReturnValue);

                DataSet ds = broker.FillCommandDataSet("LockCodeNoProc", parameters);
                //
                if (ds != null && ds.Tables.Count > 0)
                {
                    var Result = Convert.ToInt32(ds.Tables[0].Rows[0]["CodeCount"]);
                    var Bol = (ds.Tables[1].Rows[0][0]).ToString();
                    if (Bol == "True")
                    {
                        M.Result = Result;
                        M.IsSuccess = true;
                    }
                    else
                    {
                        M.Result = Result;
                        M.IsSuccess = false;
                    }
                }
                return M;
            }
        }

枚举层如下：

    /// <summary>
    /// 各个枚举的‘值’使用表名即可
    /// </summary>
    public enum CodeCateEnum
    {
        [Description("现场考察")]
        Inspection,
        [Description("非设计类过程评估")]
        EvluationPros,
        [Description("非设计类履约评估")]
        EvluationPlan,
    }

OK ,就这么多，太忙，就不做过多的演示了！

  public class PortalCodeModel
    {
        public bool IsSuccess { get; set; }
        public int Result { get; set; }
    }

说明下：当返回 IsSuccess 为 False 时，及说明发生了并发，应执行重复请求。这里采用的方式是：重复请求十次，直至成功为止！

C# 代码执行的时候，当第一次执行存储过程，会异常，请自行处理！

谢谢！