数据库生成随机数

alter proc USP_getCarID
@carid varchar(30) output
AS
declare @number varchar(50)
declare @number1 varchar(50)
declare @number2 varchar(50)
while(1=1)
begin
set @number= (select CEILING(RAND(CAST( datepart(ms,getdate()) as int))
*10000))
set @number1= (select CEILING(RAND(CAST( datepart(ms,getdate()) as int))
*4000))
set @number2='1010 3576 '+@number+' '+@number1
set @carid=@number2
if not exists(select * from dbo.cardInfo where cardInfo.cardID=@number2)
begin
break;
end
end