/******************************
*    函数名：RandDateTime
*    作用： 返回两个时间范围内的一个随机时间
*    Author:    兰习刚
*    Date:      2009-11-30
*******************************/
Go
--创建函数
create Function RandDateTime
(@RandNum Decimal(38,18),--0-1之际随机数值建议Rand()@StartTime DateTime,    --第一个时间@EndTime DateTime       --第二个时间
)
Returns DateTime
As
BeginDeclare @HourDiff Decimal(38,18)    --两个时间之间的小时差值Declare @MsPartDiff Decimal(38,18)  --毫秒部分的差值  Declare @SmallDate DateTimeDeclare @ReturnDateTime DateTime   /*取各部分差值*/Set @HourDiff = DateDiff(hh,@StartTime,@EndTime)Set @MsPartDiff = Abs(DateDiff(ms,DateAdd(hh,@HourDiff,@StartTime),@EndTime))Select @SmallDate=(Case When @HourDiff>0 Then @StartTime Else @EndTime End)    --取较小的时间 Set @HourDiff = Abs(@HourDiff)ActionLable:Declare @HourDecimal Decimal(38,18)    --小时的小数部分  Declare @HourString varchar(200)Set @HourDiff = @HourDiff * @RandNum   Set @HourString = CONVERT(VARCHAR(200),@HourDiff)Set @HourString = SubString(@HourString,CharIndex('.',@HourString)+1,Len(@HourString))Set @HourString = '0.' + @HourStringSet @HourDecimal = Convert(Decimal(38,18),@HourString)    --获得小时的小数部分Set @MsPartDiff = (@MsPartDiff + @HourDecimal * 3600*1000) * @RandNum   /*毫秒差值由于之前@MsPartDiff是两个时间小时之后的毫秒差值  @HourDecimal * 3600*1000 有小时的小数部分的毫秒差值不会大于小时毫秒不会溢出*/Set @ReturnDateTime = DateAdd(hh,@HourDiff,@SmallDate)Set @ReturnDateTime = DateAdd(ms,@MsPartDiff,@ReturnDateTime)       Return @ReturnDateTime
End--测试示例
select dbo.RandDateTime(Rand(),'2011-03-21 00:00:00.000','2011-03-21 23:59:00.000')
go 10--运行结果
/*
-----------------------
2011-03-21 16:44:58.990(1 row(s) affected)-----------------------
2011-03-21 00:00:33.313(1 row(s) affected)-----------------------
2011-03-21 15:04:58.777(1 row(s) affected)-----------------------
2011-03-21 06:32:21.347(1 row(s) affected)-----------------------
2011-03-21 15:11:51.047(1 row(s) affected)-----------------------
2011-03-21 14:39:23.597(1 row(s) affected)-----------------------
2011-03-21 07:24:17.247(1 row(s) affected)-----------------------
2011-03-21 06:15:49.653(1 row(s) affected)-----------------------
2011-03-21 02:06:14.757(1 row(s) affected)-----------------------
2011-03-21 10:49:18.370(1 row(s) affected)
*/