Generating random strings with T-SQL

Question

If you wanted to generate a pseudorandom alphanumeric string using T-SQL, how would you do it? How would you exclude characters like dollar signs, dashes, and slashes from

Answer 1

I thought I'd share, or give back to the community ... It's ASCII based, and the solution is not perfect but it works quite well. Enjoy, Goran B.

/* 
-- predictable masking of ascii chars within a given decimal range
-- purpose: 
--    i needed an alternative to hashing alg. or uniqueidentifier functions
--    because i wanted to be able to revert to original char set if possible ("if", the operative word)
-- notes: wrap below in a scalar function if desired (i.e. recommended)
-- by goran biljetina (2014-02-25)
*/

declare 
@length int
,@position int
,@maskedString varchar(500)
,@inpString varchar(500)
,@offsetAsciiUp1 smallint
,@offsetAsciiDown1 smallint
,@ipOffset smallint
,@asciiHiBound smallint
,@asciiLoBound smallint


set @ipOffset=null
set @offsetAsciiUp1=1
set @offsetAsciiDown1=-1
set @asciiHiBound=126 --> up to and NOT including
set @asciiLoBound=31 --> up from and NOT including

SET @inpString = '{"config":"some string value", "boolAttr": true}'
SET @length = LEN(@inpString)

SET @position = 1
SET @maskedString = ''

--> MASK:
---------
WHILE (@position < @length+1) BEGIN
    SELECT @maskedString = @maskedString + 
    ISNULL(
        CASE 
        WHEN ASCII(SUBSTRING(@inpString,@position,1))>@asciiLoBound AND ASCII(SUBSTRING(@inpString,@position,1))<@asciiHiBound
         THEN
            CHAR(ASCII(SUBSTRING(@inpString,@position,1))+
            (case when @ipOffset is null then
            case when ASCII(SUBSTRING(@inpString,@position,1))%2=0 then @offsetAsciiUp1 else @offsetAsciiDown1 end
            else @ipOffset end))
        WHEN ASCII(SUBSTRING(@inpString,@position,1))<=@asciiLoBound
         THEN '('+CONVERT(varchar,ASCII(SUBSTRING(@Inpstring,@position,1))+1000)+')' --> wrap for decode
        WHEN ASCII(SUBSTRING(@inpString,@position,1))>=@asciiHiBound
         THEN '('+CONVERT(varchar,ASCII(SUBSTRING(@inpString,@position,1))+1000)+')' --> wrap for decode
        END
        ,'')
    SELECT @position = @position + 1
END

select @MaskedString


SET @inpString = @maskedString
SET @length = LEN(@inpString)

SET @position = 1
SET @maskedString = ''

--> UNMASK (Limited to within ascii lo-hi bound):
-------------------------------------------------
WHILE (@position < @length+1) BEGIN
    SELECT @maskedString = @maskedString + 
    ISNULL(
        CASE 
        WHEN ASCII(SUBSTRING(@inpString,@position,1))>@asciiLoBound AND ASCII(SUBSTRING(@inpString,@position,1))<@asciiHiBound
         THEN
            CHAR(ASCII(SUBSTRING(@inpString,@position,1))+
            (case when @ipOffset is null then
            case when ASCII(SUBSTRING(@inpString,@position,1))%2=1 then @offsetAsciiDown1 else @offsetAsciiUp1 end
            else @ipOffset*(-1) end))
        ELSE ''
        END
        ,'')
    SELECT @position = @position + 1
END

select @maskedString