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

it's very simply.use it and enjoy.

CREATE VIEW [dbo].[vwGetNewId]
AS
SELECT        NEWID() AS Id

Creat FUNCTION [dbo].[fnGenerateRandomString](@length INT = 8)
RETURNS NVARCHAR(MAX)
AS
BEGIN

DECLARE @result CHAR(2000);

DECLARE @String VARCHAR(2000);

SET @String = 'abcdefghijklmnopqrstuvwxyz' + --lower letters
'ABCDEFGHIJKLMNOPQRSTUVWXYZ' + --upper letters
'1234567890'; --number characters

SELECT @result =
(
    SELECT TOP (@length)
           SUBSTRING(@String, 1 + number, 1) AS [text()]
    FROM master..spt_values
    WHERE number < DATALENGTH(@String)
          AND type = 'P'
    ORDER BY
(
    SELECT TOP 1 Id FROM dbo.vwGetNewId
)   --instead of using newid()
    FOR XML PATH('')
);

RETURN @result;

END;

Answer 2

This will produce a string 96 characters in length, from the Base64 range (uppers, lowers, numbers, + and /). Adding 3 "NEWID()" will increase the length by 32, with no Base64 padding (=).

    SELECT 
        CAST(
            CONVERT(NVARCHAR(MAX),
                CONVERT(VARBINARY(8), NEWID())
                +CONVERT(VARBINARY(8), NEWID())
                +CONVERT(VARBINARY(8), NEWID())
                +CONVERT(VARBINARY(8), NEWID())
                +CONVERT(VARBINARY(8), NEWID())
                +CONVERT(VARBINARY(8), NEWID())
                +CONVERT(VARBINARY(8), NEWID())
                +CONVERT(VARBINARY(8), NEWID())
                +CONVERT(VARBINARY(8), NEWID())
            ,2) 
        AS XML).value('xs:base64Binary(xs:hexBinary(.))', 'VARCHAR(MAX)') AS StringValue

If you are applying this to a set, make sure to introduce something from that set so that the NEWID() is recomputed, otherwise you'll get the same value each time:

  SELECT 
    U.UserName
    , LEFT(PseudoRandom.StringValue, LEN(U.Pwd)) AS FauxPwd
  FROM Users U
    CROSS APPLY (
        SELECT 
            CAST(
                CONVERT(NVARCHAR(MAX),
                    CONVERT(VARBINARY(8), NEWID())
                    +CONVERT(VARBINARY(8), NEWID())
                    +CONVERT(VARBINARY(8), NEWID())
                    +CONVERT(VARBINARY(8), NEWID())
                    +CONVERT(VARBINARY(8), NEWID())
                    +CONVERT(VARBINARY(8), NEWID())
                    +CONVERT(VARBINARY(8), NEWID())
                    +CONVERT(VARBINARY(8), NEWID())
                    +CONVERT(VARBINARY(8), NEWID())
                    +CONVERT(VARBINARY(8), NEWID())
                    +CONVERT(VARBINARY(8), U.UserID)  -- Causes a recomute of all NEWID() calls
                ,2) 
            AS XML).value('xs:base64Binary(xs:hexBinary(.))', 'VARCHAR(MAX)') AS StringValue
    ) PseudoRandom

Answer 3

I did this in SQL 2000 by creating a table that had characters I wanted to use, creating a view that selects characters from that table ordering by newid(), and then selecting the top 1 character from that view.

CREATE VIEW dbo.vwCodeCharRandom
AS
SELECT TOP 100 PERCENT 
    CodeChar
FROM dbo.tblCharacter
ORDER BY 
    NEWID()

...

SELECT TOP 1 CodeChar FROM dbo.vwCodeCharRandom

Then you can simply pull characters from the view and concatenate them as needed.

EDIT: Inspired by Stephan's response...

select top 1 RandomChar from tblRandomCharacters order by newid()

No need for a view (in fact I'm not sure why I did that - the code's from several years back). You can still specify the characters you want to use in the table.

Answer 4

Heres something based on New Id.

with list as 
(
    select 1 as id,newid() as val
         union all
    select id + 1,NEWID()
    from    list   
    where   id + 1 < 10
) 
select ID,val from list
option (maxrecursion 0)

Answer 5

Sometimes we need a lot of random things: love, kindness, vacation, etc. I have collected a few random generators over the years, and these are from Pinal Dave and a stackoverflow answer I found once. Refs below.

--Adapted from Pinal Dave; http://blog.sqlauthority.com/2007/04/29/sql-server-random-number-generator-script-sql-query/
SELECT 
    ABS( CAST( NEWID() AS BINARY( 6)) %1000) + 1 AS RandomInt
    , CAST( (ABS( CAST( NEWID() AS BINARY( 6)) %1000) + 1)/7.0123 AS NUMERIC( 15,4)) AS RandomNumeric
    , DATEADD( DAY, -1*(ABS( CAST( NEWID() AS BINARY( 6)) %1000) + 1), GETDATE()) AS RandomDate
    --This line from http://stackoverflow.com/questions/15038311/sql-password-generator-8-characters-upper-and-lower-and-include-a-number
    , CAST((ABS(CHECKSUM(NEWID()))%10) AS VARCHAR(1)) + CHAR(ASCII('a')+(ABS(CHECKSUM(NEWID()))%25)) + CHAR(ASCII('A')+(ABS(CHECKSUM(NEWID()))%25)) + LEFT(NEWID(),5) AS RandomChar
    , ABS(CHECKSUM(NEWID()))%50000+1 AS RandomID

Answer 6

Here is a random alpha numeric generator

print left(replace(newid(),'-',''),@length) //--@length is the length of random Num.