Generate N digit alphanumeric string in SQL

Today I was in a need to make a function which can generate random n digit alphanumeric string of desired length in SQL. I am writing this blog to show what I did to accomplish the same. The function accepts one parameter of integer type and will return the desired length alphanumeric output. The input parameter represents the length of the alphanumeric string which is desired . 

Below is the script for the FUNCTION:

CREATE FUNCTION [GenerateRandomNumber]
    (
      @LENGTH INT 
    )
RETURNS NVARCHAR(255)
AS BEGIN
  
	--DECLARE VARIABLES
    DECLARE @RandomNumber NVARCHAR(255)
    DECLARE @I SMALLINT
    DECLARE @RandNumber FLOAT
    DECLARE @Position TINYINT
    DECLARE @ExtractedCharacter VARCHAR(1)
    DECLARE @ValidCharacters VARCHAR(255)
    DECLARE @VCLength INT
    
    --SET VARIABLES VALUE
    SET @ValidCharacters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'    
    SET @VCLength = LEN(@ValidCharacters)
    SET @ExtractedCharacter = ''
    SET @RandNumber = 0
    SET @Position = 0
    SET @RandomNumber = ''


    SET @I = 1

    WHILE @I < ( @Length + 1 )

        BEGIN

            SET @RandNumber = ( SELECT  RandNumber
                        FROM    [RandNumberView]
                      )
            SET @Position = CONVERT(TINYINT, ( ( @VCLength - 1 ) * @RandNumber + 1 ))
            SELECT  @ExtractedCharacter = SUBSTRING(@ValidCharacters, @Position, 1)
            SET @I = @I + 1

            SET @RandomNumber = @RandomNumber + @ExtractedCharacter

        END

	
    RETURN @RandomNumber

  
   END
   
   

In the above function I have used a VIEW named RandNumberView. Script of RandNumberView

CREATE VIEW [RandNumberView]
AS  

SELECT  RAND() AS [RandNumber]

You may be thinking Why I have used it? , the answer is I need to use the random number if I had used rand() simply in the function I would have received this error "Invalid use of side-effecting or time-dependent operator in 'rand' within a function". Okay now lets test the function:

SELECT DBO.[GenerateRandomNumber](2)

--OUTPUT
-----------------------------------------
--gB

SELECT DBO.[GenerateRandomNumber](5)

--OUTPUT
-----------------------------------------
--JfAql


SELECT DBO.[GenerateRandomNumber](10)

--OUTPUT
-----------------------------------------
--QTFqjmivWW

SELECT DBO.[GenerateRandomNumber](20)

--OUTPUT
-----------------------------------------
--iZQRCEfQuTeYHLnikbWl

Do let me know your feedback, comments.