How to generate random Base36 IDs

Question

Is there a way of generating random base36 identifiers with a defined character count in SQL Server?

I have searched and found many examples of converting base 36 to int and vice versa, but not for randomly generating unique IDs.

Answer 1

This solution a bit verbose but works and can easily be adapted to a variety of requirements. Here's some sample output:

aapx0k  k4fdbb  vzbl5x
8vr1bs  gbix1q  g5kctv
he6e50  m9j0m0  2vz53l
yw72hs  hgbo5h  3oen9v
6t4q75  337670  5sf3h4
yqr35s  xoh4hh  tc0wtf
w7trkj  lnnpdk  zk2ln1
1gt7qr  l6m72n  ja5kvm
kg6f9y  6t3b7a  ujfr0i
2jatgo  0yv8rv  wvbjfa

Note that you need to create a view to wrap the use of RAND which is not allowed inside a UDF. So this solution needs two db objects, a view and a udf.

CREATE VIEW ViewRandInt AS (SELECT RAND() * 36 as RandInt)
GO

CREATE FUNCTION GetRandomBase36Id
(
    @charCount AS INT
) 
RETURNS VARCHAR(50) AS BEGIN

    DECLARE @characters CHAR(36),
            @result VARCHAR(MAX),
            @counter INT,
            @randNum INT

    SELECT @characters = '0123456789abcdefghijklmnopqrstuvwxyz',
           @result = '',
           @counter = 0;


    WHILE @counter < @charCount
    BEGIN
        SELECT @randNum = RandInt FROM ViewRandInt
        SET @result = @result + SUBSTRING(@characters, @randNum+1, 1)
        SET @counter = @counter + 1
    END

    RETURN @result;

END

-- Test:
SELECT dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6)
, dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6)
, dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6)
, dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6)
, dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6)
, dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6)
, dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6)
, dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6)
, dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6)
, dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6), dbo.GetRandomBase36Id(6)