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How to generate unique alphanumeric content in MySQL?


By : user3851608
Date : October 16 2020, 11:12 AM
Any of those help Are you sure you don't just want to use UUIDs? They're only 32 chars long, but there are near infinite combinations.
code :


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How to generate Unique alphanumeric?


By : user2924390
Date : March 29 2020, 07:55 AM
I wish this helpful for you Generate new Guid, and divide it 17 times by modulo 62. Each number you get is an index in char array described above ("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVW XYZ1234567890"). By using Guid you can guarantee that your value is as unique as Guid is.
If you are concerned with losing unique bits you may hash GUID with MD5 like this:
code :
Guid guidValue = Guid.NewGuid();
MD5 md5 = MD5.Create();
Guid hashed = new Guid(md5.ComputeHash(guidValue.ToByteArray()));

Generate a unique alphanumeric ID


By : MoonBall
Date : March 29 2020, 07:55 AM
Does that help NEWID() produces a v4 GUID. In that GUID scheme, the first 8 bytes can be any hexadecimal digit 0-F and will be composed entirely of randomly-generated data. That's not guaranteed to be unique; in fact no v4 GUID is guaranteed to be unique, it's just that the random bits (112 of 128) can represent one of 5.19 decillion numbers, so the odds of any two of them matching in the same system is infinitesimal. With only the first 8 bytes, you'll only have 2^32 combinations, which may still seem like a lot (1 in 4 billion) but by the birthday problem, after a scant 77,000 have been generated you have a 50-50 shot at generating a duplicate.

Generate unique 10 chars alphanumeric hashes in MySQL


By : Kýăw Žíń Uĉšm
Date : March 29 2020, 07:55 AM
To fix the issue you can do If you want to create unique values for this field, you can use an auto-incrementing approach, just base 36. Here is an example going up to several hundred million distinct values:
code :
update t cross join (select @i := 0, @chars = '0123456789abcdefghijklmnopqrstuvwxyz') const
    set hash = concat(substring(@chars, ((@i := @i + 1) %36)+1, 1),
                      substring(@chars, floor(@i/pow(36, 1))%36 + 1, 1),
                      substring(@chars, floor(@i/pow(36, 2))%36 + 1, 1),
                      substring(@chars, floor(@i/pow(36, 3))%36 + 1, 1),
                      substring(@chars, floor(@i/pow(36, 4))%36 + 1, 1),
                      substring(@chars, floor(@i/pow(36, 5))%36 + 1, 1),
                      '0000'
                     );
insert into vouchers(hash)
    select concat(substring(@chars, floor(rand()*36) + 1, 1),
                  substring(@chars, floor(rand()*36) + 1, 1),
                  substring(@chars, floor(rand()*36) + 1, 1),
                  substring(@chars, floor(rand()*36) + 1, 1),
                  substring(@chars, floor(rand()*36) + 1, 1),
                  substring(@chars, floor(rand()*36) + 1, 1),
                  substring(@chars, floor(rand()*36) + 1, 1),
                  substring(@chars, floor(rand()*36) + 1, 1),
                  substring(@chars, floor(rand()*36) + 1, 1),
                  substring(@chars, floor(rand()*36) + 1, 1)
                 );

How to generate unique 12 digit alphanumeric key for use in URL


By : bufalo1973
Date : March 29 2020, 07:55 AM
hop of those help? Short Answer: No.
What you're trying is not possible. You would have to keep track of the ids that you've already created. This is what a database does with index columns that increment. I also understand that URL shortening tools take new keys from a pool of generated unique ones.
code :
using System;
using System.Text;
using System.Security.Cryptography;

public class Program
{
    public static void Main()
    {
        UseAHash();
        UseTime();
    }

    public static void UseAHash()
    {
        var primaryKey = 123345;
        HashAlgorithm algorithm = SHA1.Create();
        var hash = algorithm.ComputeHash(Encoding.UTF8.GetBytes(primaryKey.ToString()));
        StringBuilder sb = new StringBuilder();
        for (var i = 0; i < 6; ++i)
        {
            sb.Append(hash[i].ToString("X2"));
        }

        Console.WriteLine(sb);
    }

    public static void UseTime()
    {
        StringBuilder builder = new StringBuilder();

        // use universal to avoid daylight to standard time change.
        var now = DateTime.Now.ToUniversalTime();

        builder.Append(now.DayOfYear.ToString("D3"));
        builder.Append(now.Hour.ToString("D2"));
        builder.Append(now.Minute.ToString("D2"));
        builder.Append(now.Second.ToString("D2"));
        builder.Append(now.Millisecond.ToString("D3"));

        Console.WriteLine("Length: " + builder.Length);
        Console.WriteLine("Result: " + builder);
    }
}

Generate unique alphanumeric IDs


By : user3484687
Date : March 29 2020, 07:55 AM
With these it helps I would suggest looking at the stri_rand_strings function from the "stringi" package:
code :
library(stringi)
stri_rand_strings(10, 3)
 # [1] "wsm" "FvH" "UXm" "14t" "rvv" "Pfo" "mzK" "20b" "O9P" "ZOr"
system.time(X <- stri_rand_strings(250000, 12))
#    user  system elapsed 
#   0.327   0.003   0.333 
length(unique(X))
# [1] 250000
head(X)
# [1] "WxRPZjt0uFaI" "E129Ug0Vif3f" "qXGzQDO0LzvG" 
# [4] "9D4guGMf2jZ1" "Qw1p7reH4XKg" "0gziFNnZ16p8"
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