Temukan jumlah total berdasarkan nilai dari tabel lain

Dengan LEFT JOIN :

select t1.name Country, count(distinct t2.name) Count
from country t1 left join cities t2 
on t2.name like concat('%, ', t1.name)
group by t1.name

Lihat demo .
Hasil:

| Country | Count |
| ------- | ----- |
| France  | 2     |
| Italy   | 1     |
| USA     | 2     |