Mysql make slug function

New update on slugify

DROP FUNCTION IF EXISTS `slugify`;
DELIMITER ;;
CREATE DEFINER=CURRENT_USER
FUNCTION `slugify`(dirty_string varchar(200))
RETURNS varchar(200) CHARSET latin1
DETERMINISTIC
BEGIN
    DECLARE x, y , z, i Int;
    Declare temp_string, allowed_chars, new_string VarChar(200);
    Declare is_allowed Bool;
    Declare c, check_char VarChar(1);
    set i = 0;

    set allowed_chars = "abcdefghijklmnopqrstuvwxyz0123456789-";
    set temp_string = LOWER(dirty_string);

    Select temp_string Regexp('&') Into x;
    If x = 1 Then
        Set temp_string = replace(temp_string, '&', ' and ');
    End If;

    Select temp_string Regexp('[^a-z0-9]+') into x;
    If x = 1 then
        set z = 1;
        While z <= Char_length(temp_string) Do
            Set c = Substring(temp_string, z, 1);
            Set is_allowed = False;
            Set y = 1;
            Inner_Check: While y <= Char_length(allowed_chars) Do
                If (strCmp(ascii(Substring(allowed_chars,y,1)), Ascii(c)) = 0) Then
                    Set is_allowed = True;
                    Leave Inner_Check;
                End If;
                Set y = y + 1;
            End While;
            If is_allowed = False Then
                Set temp_string = Replace(temp_string, c, '-');
            End If;

            set z = z + 1;
        End While;
    End If;

    Select temp_string Regexp("^-|-$|'") into x;
    If x = 1 Then
        Set temp_string = Replace(temp_string, "'", '');
        Set z = Char_length(temp_string);
        Set y = Char_length(temp_string);
        Dash_check: While z > 1 Do
            If Strcmp(SubString(temp_string, -1, 1), '-') = 0 Then
                Set temp_string = Substring(temp_string,1, y-1);
                Set y = y - 1;
            Else
                Leave Dash_check;
            End If;
            Set z = z - 1;
        End While;
    End If;

    Repeat
        Select temp_string Regexp("--") into x;
        If x = 1 Then
            Set temp_string = Replace(temp_string, "--", "-");
        End If;
    Until x <> 1 End Repeat;

    If LOCATE('-', temp_string) = 1 Then
        Set temp_string = SUBSTRING(temp_string, 2);
    End If;

SELECT COUNT(*) INTO i FROM fanpage WHERE slug LIKE CONCAT(temp_string,'%');
If i > 0 Then
	Set temp_string = CONCAT(temp_string,'-',i+1);
End If;

Return temp_string;
END;;
DELIMITER ;

P.S: change "fanpage" to your own table - this is to prevent duplicate on slug

credit goes to http://nastyhabit.wordpress.com/2008/09/25/mysql-slug-maker-function-aka-the-slugifier/