最有效的方法...唯一的随机字符串 [英] Most Efficient Way to... Unique Random String

问题描述

我需要efficently插入5个字符的随机字符串到数据库中，同时确保它是独一无二的。生成随机字符串是没有问题的，但是目前我在做什么正在生成的字符串，然后检查数据库，如果它已经存在......如果是这样，我开始了。

有没有更有效的方法来做到这一点的过程？

请注意，我不想使用GUID或其他任何超过5个字符....我一定要坚持5个字符。

PS：我不认为它的​​确与众不同，但我的琴弦都是区分大小写

。

下面是随机字符串部分。

 公共功能GetRandomNumbers（BYVAL numChars个为整数）作为字符串
    昏暗的字符作为字符串（）= {_
     A，B，C，D，E，F，_
     G，H，I，J，K，L，_
     M，N，O，P，Q，R，_
     的S，T，U，V，W，X，_
     Y，Z，0，1，2，3，_
     4，5，6，7，8，9，_
     一，B，C，D，E，F，_
     G，H，I，J，K，升，_
     M，N，O，P，Q，R，_
     S，T，U，V，W，×，_
     Y，Z}
    DIM RND作为新的随机（）
    随机暗淡作为字符串=的String.Empty
    昏暗我为整数= 0
    虽然我＆LT; numChars个
        随机+ =字符（RND。[下一页]（0，62））
        System.Math.Max​​（System.Threading.Interlocked.Increment（ⅰ）中，i  -  1）
    虽然结束
    返回随机
结束功能
 

解决方案

与按顺序添加（所以他们是唯一的）5个字符的字符串的一个大池创建一个表，并有一个GUID作为主键。添加一列，表明他们是否使用与否。

当你需要一个新的号码，你从池中的GUID选择顶部1，为了（因此它成为随机），并设置结果为花。

I need to efficently insert a 5 character RANDOM string into a database while also ensuring that it is UNIQUE. Generating the random string is not the problem, but currently what I am doing is generating the string and then checking the DB if it exists already... if it does, I start over.

Is there a more efficient way to do this process?

Please note, I do NOT want to use GUID or anything else that is more than 5 Characters.... I MUST stick to 5 Characters.

PS: I don't think it makes a difference, but my strings are all case sensitive.

Here is the "Random String" portion

    Public Function GetRandomNumbers(ByVal numChars As Integer) As String
    Dim chars As String() = { _
     "A", "B", "C", "D", "E", "F", _
     "G", "H", "I", "J", "K", "L", _
     "M", "N", "O", "P", "Q", "R", _
     "S", "T", "U", "V", "W", "X", _
     "Y", "Z", "0", "1", "2", "3", _
     "4", "5", "6", "7", "8", "9", _
     "a", "b", "c", "d", "e", "f", _
     "g", "h", "i", "j", "k", "l", _
     "m", "n", "o", "p", "q", "r", _
     "s", "t", "u", "v", "w", "x", _
     "y", "z"}
    Dim rnd As New Random()
    Dim random As String = String.Empty
    Dim i As Integer = 0
    While i < numChars
        random += chars(rnd.[Next](0, 62))
        System.Math.Max(System.Threading.Interlocked.Increment(i), i - 1)
    End While
    Return random
End Function

解决方案

Create a table with a big pool of 5-character strings that are added in sequence (so they are unique), and have a GUID as their primary key. Add a column to indicate whether they are used or not.

When you need a new number, you select top 1 from the pool, order by the guid (so it becomes random), and set the result as "spent".

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