select sum(lk), sum(usa), sum(uk)
from (
select count(*) as lk, 0 as usa , 0 as uk from customers where country = srilanka
union all
select 0 as lk, count(*) as usa , 0 as uk from customers where country = usa
union all
select 0 as lk, 0 as usa , count(*) as uk from customers where country = uk
);