Generate Random value

Wonder how random confirmation numbers are generated? Here is one way to generate. This code will exclude all the special characters and consider values from 0-9 and [a-z]/[A-Z]. But the final result will be all UPPER case characters.


 DECLARE @Lenght INT = 6
 DECLARE @OutPut VARCHAR(10) = ''
 DECLARE @ExcludeList VARCHAR(100) = '~`!@#$%^&*()_-+={[}]|\:;"''?/>.<,'
 DECLARE @CharList CHAR

 WHILE (@Lenght >0)

 BEGIN
        SET @CharList = CHAR(RAND() * 72 + 48)
        IF CHARINDEX(@CharList,@ExcludeList) = 0
        BEGIN
               SELECT @OutPut = @OutPut + @CharList
               SET @Lenght = @Lenght - 1
        END
 END

 SELECT UPPER(@OutPut)