SQL Server中的RAND函数的介绍和区间随机数值函数的实现

SELECT CHECKSUM(NEWID()) AS CheckSumValue, CHECKSUM(NEWID()) AS CheckSumValue2;
GO

 IF OBJECT_ID(N'dbo.vRandomGuid', 'V') IS NOT NULL
 BEGIN
   DROP VIEW dbo.vRandomGuid;
 END
 GO
 --==================================
 -- 功能: 随机Guid视图
 -- 说明: 具体实现阐述 
 -- 作者: XXX
 -- 创建: yyyy-MM-dd
 -- 修改: yyyy-MM-dd XXX 修改内容描述
 --==================================
 CREATE VIEW dbo.vRandomGuid
   --$Encode$--
 AS
   SELECT RandomGuid = NEWID();
 GO
 调用该视图的T-SQL代码如下：
 SELECT TOP RandomGuid
 FROM dbo.vRandomGuid;
 GO 

 IF OBJECT_ID(N'dbo.ufn_RandNum', 'FN') IS NOT NULL
 BEGIN
   DROP FUNCTION dbo.ufn_RandNum;
 END
 GO
 --==================================
 -- 功能: 获取区间内的任意一个随机数值
 -- 说明: 具体实现阐述 
 -- 作者: XXX
 -- 创建: yyyy-MM-dd
 -- 修改: yyyy-MM-dd XXX 修改内容描述
 -- 调用: SELECT dbo.ufn_RandNum(, );
 --==================================
 CREATE FUNCTION dbo.ufn_RandNum
 (
   @intMin INT,      -- 随机数值的最小值
   @intMax INT        -- 随机数值的最大值
 ) RETURNS INT
   --$Encode$--
 AS
 BEGIN  
   SET @intMin = ISNULL(@intMin, );
   SET @intMax = ISNULL(@intMax, );
   DECLARE @guidValue AS UNIQUEIDENTIFIER;
   SELECT TOP @guidValue = RandomGuid
   FROM dbo.vRandomGuid;
   RETURN ABS(CHECKSUM(@guidValue)) % (@intMax - @intMin + ) + @intMin;
 END
 GO 

 SELECT dbo.ufn_RandNum(, ) AS RandNum, dbo.ufn_RandNum(, ) AS RandNum;
 GO 

 IF OBJECT_ID(N'dbo.ufn_RandDate', 'FN') IS NOT NULL
 BEGIN
   DROP FUNCTION dbo.ufn_RandDate;
 END
 GO
 --==================================
 -- 功能: 获取日期区间内的任意一个随机日期
 -- 说明: 具体实现阐述 
 -- 作者: XXX
 -- 创建: yyyy-MM-dd
 -- 修改: yyyy-MM-dd XXX 修改内容描述
 -- 调用: SELECT @dtmRand = dbo.ufn_RandDate('--', '--');
 --==================================
 CREATE FUNCTION dbo.ufn_RandDate 
 (
   @dtmMin DATETIME,  -- 随机日期的最小值
   @dtmMax DATETIME  -- 随机日期的最大值
 ) RETURNS DATETIME
   --$Encode$--
 AS
 BEGIN
   SET @dtmMin = ISNULL(@dtmMin, '--');
   SET @dtmMax = ISNULL(@dtmMax, '--');
   DECLARE @guidVue AS UNIQUEIDENTIFIER;
   SELECT TOP @guidVue = RandomGuid 
   FROM dbo.vRandomGuid;
   -- 可以将HOUR换为DAYS
   RETURN DATEADD(HOUR, (ABS(CHECKSUM(@guidVue)) % ( + DATEDIFF(HOUR, @dtmMax, @dtmMin))), @dtmMin);
 END
 GO 

 SELECT dbo.ufn_RandDate('--', '--') AS RandDate, dbo.ufn_RandDate('--', '--') AS RandDate;
 GO 

 SELECT TOP Num
 FROM dbo.SeqDataTable
 WHERE Num BETWEEN @intMin AND @intMax
 ORDER BY NEWID() ASC; 

 SELECT TOP DATEADD(DAY, Num, @dtmMin)
 FROM dbo.SeqDataTable
 WHERE Num BETWEEN AND DATEDIFF(DAY, @dtmMax, @dtmMin)
 ORDER BY NEWID() ASC;