利用sql函数生成不重复的订单号的代码

alter function [dbo].[getordernum](
@ebaystockflag varchar(20)//规则字母
)
returns varchar(100)
as
begin
declare @dt char(8)
declare @flag varchar(20)
set @flag='b'+@ebaystockflag
set @dt=convert(char(8),getdate(),112)
declare @max varchar(100)
select @max=max(ordernumber)
from tb_ebayorder with(xlock,paglock)
where ordernumber like @flag+'%'
set @max=isnull(@max, @flag+@dt+'000')--查不到结果给个默认值
declare @a varchar(100)
declare @num varchar(10)
declare @ordernum varchar(20)
set @a=convert(varchar,right(@max,len(@max)-10))--截取数字部分
if(left(@a,1)=0)--以0开头
begin
if(substring(@a,2,1)=0)--有两个0
begin
set @num=convert(varchar,substring(@a,3,len(@a-2))+1)

end
else if(substring(@a,3,1)=0 and substring(@a,2,1)=0)--有三个0
begin
set @num=1

end
else begin --只有一个0的情况
set @num=convert(int,substring(@a,2,len(@a))+1)

end
end
else begin --数字大于100的情况
set @num=convert(varchar,@a+1)
end

if(len(@num)=1)--截取后不满三位的补0
begin set @num='00'+@num end
if(len(@num)=2)
begin set @num='0'+@num end
set @ordernum=@flag+@dt+@num
return @ordernum
end

调用：在事务中先锁定要操作的表

select * from tb_ebayorder with (tablockx)
select * from tb_ebayorderlist with (tablockx)
select * from tb_ebayorderuserinfo with (tablockx)

调用：select dbo.getordernum(@ebaystockflag)