Question

我有一些SQL代码使用以下技术生成随机数：

DECLARE @Random1 INT, @Random2 INT, @Random3 INT, @Random4 INT, @Random5 INT, @Random6 INT, @Upper INT, @Lower INT
---- This will create a random number between 1 and 49
SET @Lower = 1 ---- The lowest random number
SET @Upper = 49; ---- The highest random number


with nums as (
    select @lower as n
    union all
    select nums.n+1
    from nums
    where nums.n < @Upper
   ),
   randnums as 
   (select nums.n, ROW_NUMBER() over (order by newid()) as seqnum
    from nums
   )
select @Random1 = MAX(case when rn.seqnum = 1 then rn.n end),
       @Random2 = MAX(case when rn.seqnum = 2 then rn.n end),
       @Random3 = MAX(case when rn.seqnum = 3 then rn.n end),
       @Random4 = MAX(case when rn.seqnum = 4 then rn.n end),
       @Random5 = MAX(case when rn.seqnum = 5 then rn.n end),
       @Random6 = MAX(case when rn.seqnum = 6 then rn.n end)
from randnums rn;

select @Random1, @Random2, @Random3, @Random4, @Random5, @Random6

我的问题是这个数字代是多么随机？还有另一种方法可以做到这一点，更“随机”。

我正在使用：

Microsoft SQL Server 2008 (SP3) - 10.0.5512.0 (X64)   Aug 22 2012 19:25:47   Copyright (c) 1988-2008 Microsoft Corporation  Developer Edition (64-bit) on Windows NT 6.1 <X64> (Build 7601: Service Pack 1)

大多数解决方案的问题是你最终会得到这样的值：14,29,8,14,27,27我不能有重复的数字！

Answer 1

我想你可以做更简单，更容易的事情

DECLARE @Upper INT;
DECLARE @Lower INT;
SET @Lower = 1     -- The lowest random number
SET @Upper = 49    -- The highest random number


SELECT @Lower + CONVERT(INT, (@Upper-@Lower+1)*RAND())

要获得随机数而不重复，我认为这将完成工作

;with CTE 
as
 (
    SELECT  randomNumber, COUNT(1) countOfRandomNumber
    FROM (
    SELECT ABS(CAST(NEWID() AS binary(6)) %49) + 1 randomNumber
    FROM sysobjects) sample
    GROUP BY randomNumber
 )
SELECT TOP 5 randomNumber
FROM CTE
ORDER BY newid()

设置最高限额，您可以用最高限额

替换49

Answer 2

对于 Laravel ：

 public function generatUniqueId()
    {
        $rand = rand(10000, 99999);
        $itemId = $rand;
        while (true) {
            if (!BookItem::whereBookItemId($itemId)->exists()) {
                break;
            }
            $itemId = rand(10000, 99999);
        }

        return $itemId;
    }

Answer 3

您可以使用Rand（）函数。

select CEILING(RAND() *<max of random numbers))

使用SQL生成唯一的随机数

3 个答案: