DB: jmlah order untuk masing2 negara!!

#### CHEK : https://www.db-fiddle.com/f/d26boLZsWqWs6WaVfT7FA9/0
##########SKEMA###############
CREATE TABLE `tb_order` (
  `id` int(11) NOT NULL,
  `buyid` int(11) NOT NULL,
  `itemid` int(11) NOT NULL
);
INSERT INTO `tb_order` (`id`, `buyid`, `itemid`) VALUES
(1, 1, 10),
(2, 1, 11),
(3, 2, 13),
(4, 3, 15),
(5, 4, 17),
(6, 5, 10),
(7, 6, 14),
(8, 5, 14),
(9, 6, 11);
CREATE TABLE `tb_user` (
  `id` int(11) NOT NULL,
  `buyid` int(11) NOT NULL,
  `negara` char(3) NOT NULL
) ;

INSERT INTO `tb_user` (`id`, `buyid`, `negara`) VALUES
(1, 1, 'NA'),
(2, 2, 'NA'),
(3, 3, 'MY'),
(4, 4, 'MY'),
(5, 5, 'AUS'),
(6, 6, 'AUS'),
(7, 7, 'INA'),
(14, 14, 'MY')
;
##############QUERY#################
SELECT if(count(*)>0, 1,0) num,o.buyid,u.negara FROM `tb_order` o
join tb_user u on u.buyid=o.buyid
where o.itemid % 2 = 0
group by o.buyid,u.negara;
###########
select sum(usr) c, tb_negara.negara
from
(
select count(*) usr,u.negara from tb_user u group by u.negara
) tb_negara
group by tb_negara.negara;
##########
    select 1 c,u.buyid,u.negara from tb_order o
    join tb_user u on u.buyid=o.buyid
    where o.itemid%2=0
    group by u.negara,u.buyid;
##########
select tb_negara.negara,if(sum(nBuyer)>0,sum(nBuyer),0) c
from
(
select u.negara from tb_user u group by u.negara
) tb_negara
left join
(
    select 1 nBuyer,u.buyid,u.negara from tb_order o
    join tb_user u on u.buyid=o.buyid
    where o.itemid%2=0
    group by u.negara,u.buyid
) tb_orders
on tb_orders.negara = tb_negara.negara
group by tb_negara.negara;