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 use this procedure that I developed simply stipluate the charaters you want to be able to display in the input variables, you can define the length too. Hope this formats well, I am new to stack overflow.

IF EXISTS (SELECT * FROM sys.objects WHERE type = 'P' AND object_id = OBJECT_ID(N'GenerateARandomString'))
DROP PROCEDURE GenerateARandomString
GO

CREATE PROCEDURE GenerateARandomString
(
     @DESIREDLENGTH         INTEGER = 100,                  
     @NUMBERS               VARCHAR(50) 
        = '0123456789',     
     @ALPHABET              VARCHAR(100) 
        ='ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz',
     @SPECIALS              VARCHAR(50) 
        = '_=+-$£%^&*()"!@~#:', 
     @RANDOMSTRING          VARCHAR(8000)   OUT 

)

AS

BEGIN
    -- Author David Riley
    -- Version 1.0 
    -- You could alter to one big string .e.e numebrs , alpha special etc
    -- added for more felxibility in case I want to extend i.e put logic  in for 3 numbers, 2 pecials 3 numbers etc
    -- for now just randomly pick one of them

    DECLARE @SWAP                   VARCHAR(8000);      -- Will be used as a tempoary buffer 
    DECLARE @SELECTOR               INTEGER = 0;

    DECLARE @CURRENTLENGHT          INTEGER = 0;
    WHILE @CURRENTLENGHT < @DESIREDLENGTH
    BEGIN

        -- Do we want a number, special character or Alphabet Randonly decide?
        SET @SELECTOR  = CAST(ABS(CHECKSUM(NEWID())) % 3 AS INTEGER);   -- Always three 1 number , 2 alphaBET , 3 special;
        IF @SELECTOR = 0
        BEGIN
            SET @SELECTOR = 3
        END;

        -- SET SWAP VARIABLE AS DESIRED
        SELECT @SWAP = CASE WHEN @SELECTOR = 1 THEN @NUMBERS WHEN @SELECTOR = 2 THEN @ALPHABET ELSE @SPECIALS END;

        -- MAKE THE SELECTION
        SET @SELECTOR  = CAST(ABS(CHECKSUM(NEWID())) % LEN(@SWAP) AS INTEGER);
        IF @SELECTOR = 0
        BEGIN
            SET @SELECTOR = LEN(@SWAP)
        END;

        SET @RANDOMSTRING = ISNULL(@RANDOMSTRING,'') + SUBSTRING(@SWAP,@SELECTOR,1);
        SET @CURRENTLENGHT = LEN(@RANDOMSTRING);
    END;

END;

GO

DECLARE @RANDOMSTRING VARCHAR(8000)

EXEC GenerateARandomString @RANDOMSTRING = @RANDOMSTRING OUT

SELECT @RANDOMSTRING